Door won't unlock with key or remote. Thoughts?
 

My '01 Boxster has developed a problem with the driver's side door lock: I can't unlock the door with either the key or the remote. There's no problem unlocking the driver's door from the inside with the door handle; also there's no problem unlocking the passenger door either with the remote or with the key. The problem started after my battery was drained from non-use of the car for a few weeks--I had to take the battery out and have it recharged. The door lock issue could be caused by the battery failure or could just be coincedence. Any thoughts on what's wrong and how to fix it? Thanks very much!
Linda