sounds liek back of the lock has napped off, common fail. swap the passenger lock over for the time being, then nip to scrappy and nick another lock. strip it down and swap all the tumblers from your old lock into it then refit to the passenger handle.
i think the handle is held on with just 1 screw in the back end of the door, then the paddle has to kinda rotate 90degrees and unhook to split the lock from the handle.
another option is to fit remote central locking and delock the front doors, just make sure the boot lock works for emergencies
