It sounds like a window rolling regulator (or sliding jaw) is broken.
Only about $4, and they are prone to break. Look it up on Fastlane for a picture of it.
Pretty easy to replace once the door panel is off.
The wife has the cr today, but as I remember, you gently slide a screwdriver under the front edge of the plastic that surrounds the door handle and work it off. Then undo all the screws, etc; and lift straight up on the door panel. You will immediately spot the problem if the sliding jaw is busted.

DG