On Windows 10, whether you're using Outlook 2019, 2016, or an older version, the app stores a copy of your emails, contacts, and calendars using two different data files depending on the account type for offline access.

If you're using an IMAP or POP account, such as those provided by your Internet Service Provider (ISP), then your account information is stored inside of an Outlook Data File (PST). On the other hand, if you're using an Office 365, Exchange, or Outlook.com account, the data is stored in the Offline Outlook Data File (OST).

Usually, these data files are very reliable, but they can eventually stop working or get damaged, and for this reason, all desktop versions of Outlook bundles a repair tool to troubleshoot and fix problems with .pst files, as well as the ability to regenerate the .ost file automatically.

In this Windows 10 guide, we'll walk you through the steps to repair corrupted data files, recover missing items from your inbox, problems opening Outlook 2019, Outlook 2016, and older versions using a .ost or .pst file.

How to repair Offline Outlook Data File (.ost)

Whether you're using an Exchange, Office 365, or Outlook.com account, to fix issues with a .ost file, close the email app, and then use these steps:

1. Open Control Panel.

   Quick Tip: If you're using only the default profile named 'Outlook,' you can type this path: %LOCALAPPDATA%MicrosoftOutlook to jump directly to the location of the .ost file, and skip to step No. 12. Otherwise, continue with the steps below.

2. Click on User Accounts.

3. Click the Mail option.

4. In the 'Mail Setup' experience, click the Show Profiles button.

5. Select the profile with the account you want to fix. (The default profile is called 'Outlook.')

6. Click the Properties button.

7. Click the Email Accounts button.

8. Click the Data Files tab.
9. Select the broken account.

10. Click the Open File Location button.

11. Click the close button for the 'Accounts Settings,' 'Mail Setup,' and 'Mail' windows.

12. Right-click the .ost file for the account having issues, and select the Delete option.

Once you complete these steps, open the desktop version of Outlook again to recreate the .ost file for the account you intend to repair.

How to repair Outlook Data File (.pst)

Alternatively, in the case that you're using an email account using IMAP or POP settings, to fix problems with a .pst file, close the Outlook application, and then use these steps:

1. Use the Windows key + R to open the Run command.

2. Type the following path and click the OK button:

   C:Program Files (x86)Microsoft OfficerootOffice16

   Quick Note: The above path applies to Office 2016, Office 2019, and Office 365. If you're running Outlook 2013, use this path: C:Program Files (x86)Microsoft OfficeOffice15. In the case that you have an older version of the app, change 'Office15' in the path to 'Office14' for Outlook 2010, or to 'Office13' for Outlook 2007 in the path.

3. Double-click the SCANPST.EXE file to open the Microsoft Outlook Inbox Repair experience.

4. Click the Browse button.
5. Locate the .pst file you want to repair.
6. Click the Open button.

7. Click the Start button.

8. Check the Make a backup of scanned file before repairing option (just in case).

9. Click the Repair button.

After completing the steps, the Microsoft Outlook Inbox Repair Tool will scan and repair the .pst file for the email account with problems. Once the repair completes, you can launch Outlook, and the issues with the account should now be resolved.

Extended recovery steps

While the tool can detect and repair many issues with a .pst file, you may still need to use additional steps to recover all the items of an email account.

If this is the case, in the left pane, you'll notice a Recovered Personal Folders or Lost and Found folders, which include the repaired items that couldn't be restored.

Recovering missing items from folder

To recover items that couldn't be restored, use these steps:

1. Open the Recovered Personal Folders or Lost and Found folder.
2. Select the items you want to recover.
3. Drag and drop those items into the correct folders.
4. Right-click the now empty folder and select the Delete option.

Recovering missing items from backup

In the case that there are still items missing, you may be able to recover them from the original Outlook Data File using the backup file created by the repair tool.

1. Open the location of the .bak file. (This file is located in the same folder as the .pst file.)
2. Right-click the .bak file and select the Copy option.
3. Right-click in the folder and select the Paste option to create a copy of the file.
4. Select the .bak file.

5. Press F2 the key and rename the file to .bak.pst and press Enter.

6. Open Outlook.
7. Click on File.
8. Click on Open & Export.

9. Click the Import/Export button.

10. Select the Import from another program or file option.

11. Click the Next button.

12. Select the Outlook Data File (.pst) option.

13. Click the Next button.
14. Specify the location of the .pst file.
15. Select the Import option that you want to use.

16. Click the Next button.

17. Select the items you want to import.

18. Click the Finish button.

Once you've completed the steps, Outlook should now include all the account items.

We're focusing this guide on Windows 10 users, but if you're using an older version of Outlook (2016, 2013, 2010, and 2007), it's still possible to use these instructions on Windows 8.1 and Windows 7.

More Windows 10 resources

For more helpful articles, coverage, and answers to common questions about Windows 10, visit the following resources:

Oftentimes, Microsoft Outlook users who are leaving their current employer want to take their mail, calendar, or contacts with them and do one of two things: delete the Microsoft Exchange account from their profile without realizing the Contacts are stored in the Exchange account or they take the OST file with them, not realizing it can only be opened using the account that created it.
If you have the OST file but no longer have access to the computer that created the OST or you don't have a restore point, you'll need to use a tool to recover the contents of the OST. A list of these tools is below.

Beginning with Outlook 2013, Outlook was designed to permanently delete the OST data file when the account is removed from Outlook. If you deleted the account from Outlook and did not export the contents to a pst file or copied the OST file, your chances of recovering data is not good. You will need to use software to undelete files from your hard drive, but successful recovery depends on how much time has passed between deleting the account and running the undelete software as Windows will overwrite the deleted files. To see if the OST exists, type or paste %localappdata%microsoftoutlook into the address bar of File Explorer. Many of the companies that have OST to PST recovery software also have file recovery software.

There are number of file recovery programs available, including these utilities from our sponsors: DataNumen NTFS Undelete (Free), DataNumen Data Recovery, Kernel for Windows Data Recovery, and Stellar Phoenix Windows Data Recovery

If your company uses a group policy that blocks PST creation, your choices are limited to exporting calendar and contacts to CSV (or Excel, if you have Excel at home). If you don't have many calendar or contacts, you can forward them to a personal address. If using Outlook 2007 or newer, you can send your entire calendar as an iCal.

Check company policies before taking home the contents of your mailbox.

Restore Exchange Account

If you deleted the Exchange account, you may be able to recover the account if your operating system supports system restore and you only recently deleted the account. If too much time has passed you are less likely to have a restore point available.

This method will also work with IMAP accounts in Outlook 2013 and up IF you have a copy of the IMAP data file.

Outlook 2013 and up automatically delete the account's OST file when the account is removed from Outlook. The only way you'll be able to use this method is if the OST file exists (because Outlook failed to delete it. It's rare, but it does happen.) To check, look for the OST at %localappdata%microsoftoutlook before doing a restore.

1. Open the System Restore application. In Settings or the Search field on the taskbar or Start menu, type restore then select Create a restore point in the search results. Click the System Restore button to open the System Restore wizard. You can also open it by typing or pasting rstrui.exe in search field or in the Run command.
   
2. Pick a date just before the profile was deleted then follow the steps in the wizard.

When Windows restarts the account will be back and you can move or export the contents of the OST to a PST. Then either delete the account or run restore again to return to the point made before the restore, after backing up a copy of the newly created pst file.

Method 1: Archive

You may be able to use Archive to move or copy many items to a PST. Users Exchange online archive mailboxes will not be able to archive to a pst.

Autoarchive works best when you want to move almost everything in your mailbox, however, you cannot archive Contacts. You'll need to move or copy contacts to the pst file or use Export.

Set the AutoArchive default in File, Options, Advanced, AutoArchive and apply the settings to all folders. (The AutoArchive button the Folder ribbon allows you to set a specific archive setting for the current folder.)

Then go to File, Tools, Cleanup, AutoArchive to run it.

AutoArchiving uses the last modified date so you'll need to use a low number of days when archiving recent items. In Outlook 2007 and newer, you can force AutoArchive to use the Received Date. See Using Microsoft Outlook's Autoarchive feature

If you use this method and also need the Contacts, you'll need to move them to the new data file.

Method 2: Export to a PST

Although Export is not usually recommended, it works well for moving content from an OST to a PST file. You can export all content from the OST to a PST or just the calendar and contacts. If your company blocks the creation of PST files, export Contacts, Calendar, and Tasks to CSV or Excel format.

You'll use this method if you are moving to a new server and need to migrate your own email (or if the server died and there are not backups). Make sure you start Outlook offline so that you don't connect to the new server; connecting to the new server has the potential to delete the mail in the offline file. Export everything to a pst then remove your account and use auto account setup to add it back to your profile.

Method 3: Move the items to a new PST

Create a new PST in your profile and drag the folders you want to take with you to the PST. This method will preserve custom views and forms published to folder.

Dragging default folders, such as Inbox, Calendar, and Contacts, brings up a message that you can't move default folders. The contents will be copied instead, with the folder named Inbox (1), Calendar (1), etc.

Method 4: Forward by E-mail

If you don't have too many items you want to keep, you can email them to your personal email address. Select the item(s), right click and choose Forward or click Ctrl+F. If you have a lot of messages you want to keep, you could drag them to a folder in Documents, then zip the folder and email the zip file.

If you forward the messages to an account that is opened in Outlook, you can drag attached messages from the incoming message and drop it in the Inbox or another folder.

If you are using Outlook 2007 or newer, you can email the entire calendar as a single iCal, provided you use Outlook or another calendaring application that supports multi-event icals at home. Outlook 2003 and older versions of Outlook do not support multi-event icals.

To create the iCalendar file, you can right click on the Calendar folder and choose Share, Email Calendar. If you want to create the iCalendar file and do something with it later, select the calendar folder, then go to File, Save Calendar.

When you use Email calendar, a dialog will let you choose the date range and other options. If you are saving the calendar to your hard drive, click More Options in the Save as dialog to open this dialog.

The defaults are Today and Availability only; you'll most likely want to use whole calendar and full details. Note that some calendars don't support attachments; if you are including attachment you should save a second copy that does not include attachments.

OST to PST export utilities

If you have an orphaned OST and can't recover the account using System Restore, you'll need to use a utility to export the contents to a pst file.

The free OST2PST utility will only work with OST files created by Outlook 2002 and older. If you aren't sure what version of Outlook you used, try it; an error means the OST is not the correct type.

Tools in the Spotlight

Tools

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