There are chances for PST files got corrupted or got accidentally deleted from your account. These are two main possibilities for PST data to get disappeared in no time. ‘Outlook cannot access PST file’ is a common Outlook pop up error message occurs due PST file corruption. But, since you couldn’t find your PST files anywhere on the local drives, repairing PST files using Inbox Repair Tool is not possible. Now the chance is for accidental deletion. Deleted files can be recovered manually from Deleted Items Folder.
If PST files are permanently deleted, it is difficult to recover it back manually. In such cases, you have to go for some reliable Outlook PST File Recovery software available in the market.
Note: This can also occur if you have upgraded your MS Windows or Microsoft Office recently without taking a backup of PST files.
Hope this will help you.
Thanks & Regards,