If your electric motor is good as you say, then it's your switch that has gone bad. The contacts on the the window switch are bad and you might get away with spraying some electrical contact cleaner in to the unit and that might buy you a few more years of service.
The contact points wear out and corrode due to time and moisture throughout the years of service, start with trying to clean the switch and if that does not work. Replace the switch, good luck and keep us posted. Be glad to help you get your window working again soon.