Sounds like a sheared pin or broken shaft on the motor. You are going to have to pull the motor off the transmission and inspect the gear
This is a worm gear it should turn. If not. Gear not engaged to shaft or shaft not shafting. (Turning). but if you hear the motor running. Well that limits it to Gear not engaged. Never heard of that happening before on those motors.
The bad news. You may need to buy a new motor (Very expensive for OEM)
the good news: it is a very INexpensive Window riser motor you can get at Auto-parts-r-us type places (Long list of auto parts stores omitted).