Back driver door won't lock or unloc without manualy doing . 2008 chevy impala

I would say a Body Shop

take yor remote to a cobler key shop should be abel to help

Locate the rear door actuator motor and check for power at its wiring when you operate the remote. If power is there, but no action, then replace motor/actuator.
If no power is present, then check the wiring and the relay within the central locking circuit box.

There is a window lock button that diables all windows but the drivers window, check it.

gm had a problem with the door lock actuators take the door panel off and check for power and ground at the actuator

I had the same problem but on the passenger side door. The wire harness on the passenger side had broken wires. Purple wire was for the lock and thicker blue and darker grey was power for the windows. I used butt connectors to repair and it worked like a charm. Area was tight to work in between vehicle frame and door. Was easier to remove door panel and disconnect harness at vehicle frame and pull harness through door to complete the repair.

is the child safety lock on?

I have problems with all door locks. Some work some others don't. Or right side of the car won't lock or unlock. Or the left side won't unlock or lock. Or they all work great . When it's very hot outside none will or will.What's the problem.

Most cars these days have this designed into the window system. Its a safety issue and I'm afraid there may nothing you can do. If there is more window track below the bottom of the glass, look for stops bolted or rivited in the track. If so, you may be able to move them down. However, this is dependent upon the drive mechanism, which may also limit window travel.

Passenger side of the fender under the hood - check the fuse relay box - about $12.00 a piece - they do go bad from time to time.
exchange the power lock relay with another one and test the locks.
then put the relay back and go to the autostore.