[rfoulds]

If you are definitely hearing the motor when you press the button or lift the door handle but the window does not move, then the lift arm has disengaged.
If the window is so lose that it wants to drop down into the door by itself, then it has slipped off the tracks.

Its more likely that the lift arm has disengaged somehow. You can pull the door panel and look yourself but only use the proper door trim removal tool to undo the snaps. If you try to pry it off using a flat edge tool, you will most likely damage the panel and the clips holding it.

If you don't have the tool or can't get one, take it to an auto glass shop and have them fix the window lift. They have the correct trim tools. It isn't worth damaging it.