Doors stay locked

Ok! I bought this as a little runner for 2500 miles a year. The key is old and wont work the central locking, no big problem I'm old enough to remember doing it the old way Lol. I have been using it manually but suddenly the driver door opens but all the passenger doors stay locked. I've checked the fuse and its ok. The door catches rise but the handles are mechanically dead.
Any ideas have I somehow by accident upset the system.