Angry [Q] HUGE MISTAKE. Erased int sd-card

So my sister, who owns a s3 complained about lag so I told her I could make it better by installing cyanogenmod. I installed recovery and everything, factory reset from cwm and then flashed. It installed well. But now her whole internal sd card got erased by the factory reset (including the backup I made). I had no idea this was gonna happen as I myself dont own a s3. She is really pissed off at me cause she had a really really really important recording in her internal sdcard. Now my question is. Can I use a windows software tool to restore her internal sdcard (like you can on harddrives) or will that mess up the system partition??

Need expert help. Thank you so much, sincerely
Hit THANKS if I helped

WALKMAN ROM for Optimus 3D