I assume you have remote central locking ?
If so, sounds like the little plastic retaining clip has given up the ghost.
Remove the interior door panel and that will give access to the inside of the lock mechanism.Press your key fob and see if the little piston works (should here a 'clunk' as well) If that works ok, look closely at the cable that pulls the lock down. Does it move ? There is a small white plastic clip which often comes detached/breaks which connects the cable to the door pin. Hope you have thin fingers
