Do you hear the motor running? Did you inspect the track to see if something is stuck in the seats track like a coin or some other obstruction?
There a few other possiblities but one should bring this to a reputable repair shop for proper diag.
If you need this diagnosed properly you can call one of our four stores @
1) Willowbrook (281) 890-9400 3) The Woodlands (281) 465-9410
2) Champions (281) 370-7900 4) Cypress (281) 304-7833