best you remove the door inner panel- wire connector at motor or switch could be loose, off- even possible the wires have been pinched where they go thru the door edge- mainly- see inside the door at the wires coming thru- use a knife of razor blade to slit the outside covering but carefull to not cut wires- volt/ohm meter is best to see if you have current running to the switch- to the motor- sort of have to see if you have a break anywhere-
I'd remove the inner door panel, see and inspect connections and wiring loome (wire covering) for pinch or tear- sort of have to trace wires one at a time- have paper and pen handy for notes- take down as many as you need
another person to help is not a bad idea
kind of best you do the inspection- shops usually charge quite high to find wiring, connection problems-
think of it this way- expect the worse- most likely it's something simple-