How do I take door panel off

A couple of weeks ago when I put the key in the door the chamber slipped in. For a while I was not able to lock my door until I left my keys in the car, then it locked. Anyway I got in the car but now I cannot open the door from the inside or outside. Is there any way to take the door panel off with the door closed. If not what can I do and if so then how exactly do I do it?