Because the window probably jumped the track or the track has become disconnected somehow. Pull the door panel off and you should easily be able to determine what it is and fix it. well the motor is connected with some belt or any other thing to move the window may be that belt got sliped from motor or broken due to this motor is running freely.
Salvage yard would be an inexpensive choice.
Its possible you:ve blown a fuse, I would check them first.could also be window motor or your main window control
the window motor might be bad or there is not of power in your cords to power it
Check your fuses, check for power going into the window motor, exc.
the motor and the switch both work but the window will not move
It is possible that the power window motor and the blower motor are both faulty or that you have faulty wiring.
There is no single fuse for one power window. The most common thing is the switch to fail. This would be the master window switch. Try jumping the wires with a live current and see if the window goes up and down. If it does then its your switch, if the motor fails to move most likely its the motor/regulator.
I would suspect an intermittent short in the wiring to the power window motor in the section between the door and the door jam.
Cause the window motor is out
If the passenger side works fine and there is no power at the driver side motor, I would suspect the switch. A weak motor will overheat the switch causing it to melt inside where the contacts are.
A faulty power window switch or faulty wiring. The motor works in either direction (there is only one motor per window), so it's not the motor but the wiring or the window switch. Unless the motor control is damaged, that is. Check the switch for continuity first, then check the continuity of the wiring. If you don't find the fault in either of those places, check the motor assembly. Post back here with your findings. Thank you.
I would suspect the switch first. The next time it fails remove the door panel, unplugg the electrical connection at the window motor and probe the plug with a test lamp to see if the motor is receiving power when you work the switch.