Is this a 4 or 4s? What is the model number on the back? If its A1431 or A1387, it is a 4s, and does indeed have a sim tray. A1349 or A1332 will indicate an iphone 4.
And when you say "reset", do you mean she did a wipe of your phone, aka Factory Data Reset, aka "Erase all Content and settings"