done this myself loads of times ,
tools needed
metal coat hanger and 2x screw drivers .
straighten coat hanger , put a hook on it about 1 and a half inch at the end , prize top of door open in front of the rubber with screwdriver nr the back of the door (front door)where it joins rear door and roof , use another screwdriver to hold it open while you place the coathanger behind the door lever ( on inside of car ) and twist , you will need to be patient as it took me ages , the hook will not hook around the lever as it is flush at the bottom .
good luck