If not the motor or switch, it could be the wiring at the door hinge. On my car, the plug was very corroded and the little pins broke inside. I just added some wires and spliced them together.

You can test the window motor by applying voltage from a battery. Just swap the wires around to make it go up or down.

I also took a switch apart once and repositioned the little brass rockers that makes contact, that worked also.

Has any testing been done with a meter?