How to Repair a Corrupt Outlook Data File with ScanPST

Outlook crashes, freezes, or shows missing/empty folders — classic signs of a corrupt .pst data file.

Why: A PST can become damaged by an improper shutdown, a full disk, or a very large file. Microsoft ships a free Inbox Repair Tool, ScanPST.exe, that scans and repairs the file’s structure. Back up the PST first — it’s your only copy of that mail.

Fix 1: Find ScanPST.exe

Close Outlook completely, then open the folder for your version in File Explorer:

• Microsoft 365 / Outlook 2021 / 2019 / 2016: C:\Program Files (x86)\Microsoft Office\root\Office16
• 64-bit installs: try C:\Program Files\Microsoft Office\root\Office16
• Outlook 2013: C:\Program Files (x86)\Microsoft Office\Office15

If it isn’t there, search the C: drive for scanpst.exe. Double-click it to launch.

Fix 2: Locate your PST path

You’ll need the file’s full path inside ScanPST.

1. Reopen Outlook briefly → File → Account Settings → Account Settings → Data Files tab.
2. Note the full path of the .pst (click Open File Location to confirm).
3. Close Outlook again before scanning.

Fix 3: Scan and repair

1. In ScanPST, click Browse, select your .pst, and click Start.
2. Let it scan (large files take a while). If it reports errors, tick “Make backup of scanned file before repairing” and click Repair.
3. When it finishes, reopen Outlook and check your folders. Severe corruption may need several passes — run Repair again until it reports no errors.

Fix 4: For an Exchange OST, preserve unsynced data before rebuilding

For an Exchange/Microsoft 365 .ost, compare Outlook with the web mailbox first, including mail, calendar, contacts, Drafts and Outbox. Export any local-only items to a PST through File → Open & Export → Import/Export → Export to a file → Outlook Data File (.pst) and verify the export before rebuilding. Unsynced data may exist only in the OST; a renamed OST is not a substitute for an export. Stop if you cannot preserve important items.

Then close Outlook, find the correct account’s .ost path in Data Files, rename it to .old, and reopen Outlook to download server data. Keep the old file and the PST until you verify the rebuild and restore any missing exported items. Do not apply this Exchange-cache procedure to a PST or to IMAP folders labeled This computer only without separately preserving their contents.

FAQ

Will ScanPST delete my email? It repairs structure and can drop unrecoverable items, which is why you tick the backup option — it saves a .bak copy of the original before changing anything.

ScanPST says it can’t repair the file — now what? If repeated passes fail, the PST is too damaged for the built-in tool. Restore from your most recent backup, or recover what you can by creating a new PST and dragging readable folders into it.

Sources: Microsoft Support — Repair Outlook Data Files (.pst and .ost)

Additional sources: Microsoft — preserve unsynced items before OST deletion