Driver door window off track, will not roll down

The driver door window appears to be off the track. When pressing the power button to lower it down, the window comes down about an inch then gets sideways and jams. The forward part of the window, closest to the rear view mirror drops down but the opposite side, near the outer door handle, hangs up. When press the power button to raise it, the window goes back up but will not stay inside the track. Can you tell me the procedure to get the window back on track?