<<My mom allowed a friend to change the operating system on her laptop.>>
Why? Why the change?
What is the new O/S...what was the old?
Does the system run without problems now?
You can try data-recovery software...nothing to lose but time. Some which members have used successfully:
Partition Find and Mount — free partition recovery software - http://findandmount.com/
Recovery Software, Partition Table Doctor - http://www.ptdd.com/
Recovery Software, Recover My Files - http://www.recovermyfiles.com/
Recuva - Undelete, Unerase, File and Disk Recovery - Free Download - http://www.piriform.com/recuva