Probably broken wires where the door meets the door pillar. The constant flexing of the wires as the door opens and closes can eventually cause the wires to break. Causes an open circuit. If that is the case the you may be able to connect extra pieces of wire each side of the breaks to "leap-frog" the open circuits. That would be the quickest way using something like ScotckLok connectors.
To check, you need to check that power is getting to the switches and central locking actuator in the door. If it isn't then you need to fix the wires mentioned above.
If power IS getting to the window switches and the actuator then you need to explore further:
eg. fuses
switches
window motor
c/l actuator
Good luck, let us know how you get on.
ChicksFan, July 2011