My pictures folder changed and are all missing?

Very odd. A friend of mine just signed up and joined ATS using my computer. Her 2 pictures are in my picture folder and all my 60 some images are gone! We signed in to hers to see if mine were in hers but they are not.

How can her avatar images be on my pictures and mine are gone?? I had a smiley's folder, as well and all picture folders are gone, only showing her 2 images.

Thank you for any help.