If your levelers are also inoperative it most likely is the "switchblade" type resettable fuse (circuit breaker) under the entrance steps. The fuse is the one that has the red test button and if it has tripped there will be a blade (plastic) sticking out the bottom. To reset fold the blade back into the fuse housing. Hope this is the problem and can easily be resolved for you. Could be any number of things if this procedure does not fix your issue.