Outlook actually comes with a built-in repair tool called ScanPST.exe that’s designed to scan and fix issues in your PST files.
• Close Outlook completely.
• Run SCANPST.EXE.
• Click Browse and locate your PST file — by default it’s usually in: C:\Users\<YourUsername>\Documents\Outlook Files\
• Click Start to scan the file.
• If issues are found, click Repair.
• Once done, open Outlook and see if it loads the data.
If ScanPST doesn’t fully resolve the issue due to large PST file or the corruption is too severe, third-party tools offer deeper recovery options. One tool that I will recommend:
Stellar Repair for Outlook
• Recovers all mailbox items: emails, attachments, calendars, contacts, tasks, etc.
• Can repair large or severely damaged PST files.
• Allows preview of recoverable data before saving.
• The Technician version supports exporting to Office 365 or Exchange, and even splitting/compacting PST files.