Using classic Outlook for Windows in business environments
Verify that the path and file name is indeed exactly the same as where you've placed the pst-file now.
What are the exact notifications/errors that you get?
Is this pst-file linked to a POP3 account or is it just an extra pst-file you created to archive items to from your main mailbox?
As you can still successfully start Outlook, you can disconnect the pst-file via;
File-> Account Settings-> Account Settings...-> tab Data Files
After that, restart Outlook and verify that the notifications/error are gone.
You can then connect the pst-file again via that same dialog.