Help the window up while pushing the button. Open the door and squeeze the glass between both hands and lift it up if you have a helper to push the "up" button. The motors are much more likely to have gone weak, too weak to overcome the rusty scissor jack of the infrequently used regulator and dried grease. Also, press down, then up - there's a bit of play in the motor designed to get them up to speed before engaging.
Taurus curse. I added a long spring to help lift one back window (better stuck up than down), but it also made a spring sound needing rubber tubing.
If there was something stripped in the motor, it might be the worm gear, but that would take force these motors just can't put out. The window drops to the bottom if the teeth of the main output motor cog are stripped, not engaging the regulator, or the motor is removed.
The rear motors are more of a pain than front. They come out with just removing three bolts and bending the bracket back while weaseling and wiggling the motor out. The "easy way" is to drill the rivets and use new aluminum rivets after vacuuming out shavings and pieces from the bottom of the door.