Before you take everything apart, I would unhook the wires from the motor and test them to see if any voltage is present when you push the switch. If no voltage than your switch may be bad.

If voltage is present, than maybe your motor is bad or your regulator is stuck? It is made out of pot metal and will warp out of shape over time making the gears lose contact or eventually the regulator will snap from the torque.

You can undo the regulator and pull the glass. You can remove the motor and test it to see if it is seized.

I've had to replace two broken window regulators before. The lack of grease on the linkage over time causes a lot of stress on them.

I have never had to replace a motor. I wonder if they are rebuildable? I would imagine so. They are sort of hard to get at if I remember correctly.

I've replaced lots of switches before. They go bad more often than the motors.