I just thought I'd post this in case anyone was having the same problem. A few months ago, my door unlock button quit on the driver's side. All of the doors would still lock/unlock with the fob or the passenger side button. I took the switch apart and cleaned it but it still didn't work. I used my test light and found that a wire that should've had power didn't. I ended up tracing the problem to the flex joint in the door jamb that all the wires go through. Over time the pink wire with the green stripe fatigued and broke in half. I just had to splice it back together and problem solved. My Explorer only had 80K miles when this happened so I bet alot of other ones have similar broken wires that could affect any of the door button functions.

Anyway, hope this helps someone.

-Evan

Thanks for the heads up.
That is a common problem on many vehicles.
Of course the majority of the time on the drivers door, for obvious reasons.