How do you remove a picture that is stuck to the glass of a frame?

My parents have only one picture from their wedding, and it somehow got stuck in one spot to the glass part of the frame. The glass actually got cracked when the frame was dropped, but we can’t replace it because we are afraid of tearing the picture. Does anybody know if it can be steamed off or something without being damaged? If so, where could i get this done at? THanks for your help!