Doing this to my manager's car this week

What happens? Does the motor click when you press the window switch? Does one switch make it click, and the other do nothing, or does nothing happen at all?
Take off the door panel, unplug the motor connector, and put a meter in there to see if you're getting power when you press the switch. If you are not getting power, the switch is gone. If you are, it's most likely the motor.
changing it is just a case of removing the 3 nuts (10mm) on the motor, and the 3 that hold the mechanism to the door, as well as the 2 that hold the glass to the mechanism - tricky if it's stopped closed, but you can just about reach them

stick a block of wood between the frame and glass to hold it still, pull out the old mechanism/motor assembly, and fit the new one
