Win XP Home, MS Office 2007, Outlook

I'll try to keep this simple even tho it's frustrating as hell.

Evidently, someone, somehow deleted some files from a computer. One folder may have contained the Outlook password. This employee
now, can't retrieve her email. Our IT guy is out sick, I'm fairly savvy with OS's and harware so I'm trying to fix the problem.
I tried creating another account but that didn't work.
For my next trick, I trying to backup all the .pst files, uninstall/reinstall the program and then return the files.

Problem.... can't find the .pst files.... anywhere.

Checked default location.... nothing.

Yet, open the Outlook program and all the emails. including attachments are all there.

Anybody tell me where they're hiding at?