How to fix .pst file error

First, go to the Outlook app.

Select File > Account Settings > Account Settings.
Select the Data Files tab.
Mark the path to this folder where the .pst file is located.

Close Outlook and open Windows File Explorer. Navigate to this folder:
C:\Program Files (x86)\Microsoft Office\root\Office16

Open SCANPST.EXE
Browse to your PST file and start the repair process.
Choose Start to begin the scan.
If the scan finds errors, choose Repair to start the process to fix them.
After the repair is complete, see if the problem persists.

Source;https://support.microsoft.com/en-us/office/repair-outlook-data-files-pst-and-ost-25663bc3-11ec-4412-86c4-60458afc5253

You may see the “.pst file missing” error if Outlook is unable to locate your data file because it was moved, renamed, or deleted. A quick way to check is:

In Outlook, go to File > Account Settings > Account Settings > Data Files and confirm the PST path.

If the file was moved, use Browse to re-attach it. You can also search your PC with *.pst to locate it.

If the file is found but won’t open, run SCANPST.EXE (Inbox Repair Tool) to repair it.

If the PST is completely gone, try restoring from a backup or File History/OneDrive if enabled.

To prevent this in the future:

Avoid keeping PSTs on external or network drives (they often disconnect and cause errors).

Keep regular backups of your PST files.

Use Online Archive in Microsoft 365 instead of relying too much on local PSTs.

• Keep PST sizes manageable (ideally below 10–15 GB).You may see the “.pst file missing” error if Outlook is unable to locate your data file because it was moved, renamed, or deleted. A quick way to check is:
  1. In Outlook, go to File > Account Settings > Account Settings > Data Files and confirm the PST path.
  2. If the file was moved, use Browse to re-attach it. You can also search your PC with *.pst to locate it.
  3. If the file is found but won’t open, run SCANPST.EXE (Inbox Repair Tool) to repair it.
  4. If the PST is completely gone, try restoring from a backup or File History/OneDrive if enabled.
  To prevent this in the future:
  • Avoid keeping PSTs on external or network drives (they often disconnect and cause errors).
  • Keep regular backups of your PST files.
  • Use Online Archive in Microsoft 365 instead of relying too much on local PSTs.
  • Keep PST sizes manageable (ideally below 10–15 GB).