Window problem

Kinda wierd problem. I took my car to the shop to have new wires put in. I got it back and now my rear passenger window doesnt work. You can hear the motor go up and down, but the glass doesn't move. However, u can move the glass with your hands, not super light but its possible. Anybody know how to fix the problem. Im thinkin that the spot where the motor connects to the glass is somehow unattached...hopefully not broken. Anyone know how to fix this(myself)? And if i have to take off the panel, which i would, how do you do that as well? thanx