After Scanpst opens, click Browse and browse to the location of the PST. Or paste the following line in the File name field and click Open. This will open the default PST location in the file browser.
%USERPROFILE%\Local Settings\Application Data\Microsoft\Outlook
This path works in all versions of Windows if Outlook created the .pst in the local application data path. If you moved the .pst or Outlook 2010 created the PST file in My Documents, you'll need to click Browse.

Select your PST from the list (most people will have just one) click Open, then Start to begin testing the PST

When Scanpst is finished running the tests, a dialog reports the errors found. If you need to repair the PST, always make a backup.

Apply guide for Scanpst, if it isn't working that denotes your .pst corruption is more complicated and you would see following resource...
https://www.repairtoolbox.com/how-to...-pst-file.html Outlook Repair Toolbox