If the gears to the motor are out you can move the glass by hand,but most often the electrical component of the motor is out for one reason or another. If this is the case you can jump the motor with a cordless drill battery (even a small one will do). First get a cordless battery and 2 wires have one person hold the 2 wires on to the battery connections while you put the wires into the connections that are on the motor. The window will move up or down, if it moves up and you want it to move down reverse the wires you are holding onto the motor connections.
I know your thinking well if the electrical is out on the motor how's it going to work well simple the motor draws power when slight electrical malfunctions occur the amount of power the motor is drawing will not do it anymore due to the motors electrical components not pulling enough juice. By using the battery you are boosting it with 12,or 18 volts whatever battery you are using this will not hurt the motor or wiring and can get your window up in place till you get a motor or down in the place to remove the glass retainers. Also if this is the case and you want to try to fix the motor which often only requires cleaning it go on youtube and you'll find a video on that.