hi jo, It could be the door latch isn"t working if it is a patio door you can put pressure on the door at the bottom and on the right hand side on the frame there should be a catch at the bottom,get a small screwdriver ant flick the catch out wards this will release the the bottom of door repeat on the top once they are free push both doors and they should open.
regarding the key if you put another key in the opposite side and tap it the other one should come out enough so you can grab it with a pair of pliers I am a locksmith so any probs look on yell.com for key solutions in deal kent. regards mick
mick the pick, January 2007