If your Microsoft Outlook Data File (.pst and .ost) won’t open or you suspect that the data file is damaged, use the Inbox Repair tool (Scanpst.exe) to diagnose and repair errors in the file. The Inbox Repair tool checks the Outlook Data Files on your computer to see if they're in good shape.
Repair a .pst file
Exit Outlook, and browse to <drive>:\Program Files — or, if you see a Program Files (x86) folder on the same drive, browse to that instead. For example, C:\Program Files or C:\Program Files (x86).
In the Search box, type Scanpst.exe.
If the search doesn't find Scanpst.exe, try searching in the alternative folder mentioned in step 2, above — Program Files or Program Files (x86).
In the Enter the name of the file you want to scan box, enter the name of the .pst file you want the tool to check, or click Browse to select the file.
By default, a new log file is created during the scan. Or, you can click Options and choose not to have a log created, or to have the results appended to an existing log file.
If the scan finds errors, you're prompted to start the repair process to fix them.
The scan creates a backup file during the repair process. To change the default name or location of this backup file, in the Enter name of backup file box, enter a new name, or click Browse to select the file you want to use.
A copy of the log file is saved to the same folder as the .pst file.
Start Outlook with the profile that contains the Outlook Data File that you repaired.
Switch to the Folder List view in the folder pane by pressing Ctrl+6.
In the Folder Pane, you might see a folder named Recovered Personal Folders that contains your default Outlook folders or a Lost and Found folder. Although the repair process might recreate some of the folders, they may be empty. The Lost and Found folder contains any folders and items recovered by the repair tool that Outlook can't place in their original structure.
You can create an Outlook Data File, and drag the items in the Lost and Found folder into the new data file. After you've moved all the items, you can remove the Recovered Personal Folders (.pst) file. This includes the Lost and Found folder.
If you can open the original Outlook Data File, you may be able to recover additional items. The Inbox Repair tool creates a backup file with the same name as the original, but with a .bak extension, and saves it in the same folder. You may be able to recover items from the backup file that the Inbox Repair tool couldn’t recover.
To recover items from the backup (.bak) file, make a copy of it and give the copy a new name with a .pst extension, such as bak.pst. Import the bak.pst file into Outlook, and then use the Import and Export Wizard to import any additional recovered items into the newly created .pst file.
Learn how to import a .pst file by reading Import email, contacts, and calendar from an Outlook .pst file.
Re-create an offline Outlook Data File (.ost)
Some account types, such as Microsoft Exchange Server, use an offline Outlook Data File (.ost). This type of data file is a copy of information saved on your mail server. If you encounter problems with an offline Outlook Data File (.ost), the file can be re-created by downloading a copy of your items again. We don't recommend repairing an offline Outlook Data File, so if your offline data file isn't usable, you should re-create it by doing the following:
In Control Panel, click or double-click Mail.
Where is Mail in Control Panel?
Mail appears in different Control Panel locations depending on the version of the Windows operating system, the Control Panel view selected, and whether a 32- or 64-bit operating system or version of Outlook is installed.
The easiest way to locate Mail is to open Control Panel in Windows and then, in the Search box at the top of the window, type Mail.
Note: The Mail icon appears after Outlook starts for the first time.
The title bar of the Mail Setup dialog box contains the name of the current profile. To select a different existing profile, click Show Profiles, select the profile name, and then click Properties.
In the Mail Setup dialog box, click E-mail Accounts.
Click the Data Files tab, select the Exchange account, and then click Open File Location.
A file explorer window opens to the location of the data file for the Exchange account. The Account Settings and Mail Setup dialog boxes will remain open, behind the file explorer window.
Close the Account Settings and the Mail Setup dialog boxes, then return to the file explorer window.
Important: Be sure to close these two dialog boxes before you delete the file. If they aren't closed, Windows may display an error message about a conflict.
In the file explorer window, right-click the Exchange data file and then click Delete. The next time you start Outlook, a new .ost file is created for the account.