There may be a reset button (circuit breaker) built in. If so, reset it.
If not that, the motor could have died. Not an uncommon failure mode on these units.
You can probably get parts and repair it yourself, if you are mechanically inclined, but if it is the motor, I suggest replacing it. I use Genie screw drive GDOs. You can get them at a home center. They are reliable, and the new ones have two safety features plus the rolling code security feature.