Model number? As for what could be wrong, obviously it's broken, I know
that's not the answer you're looking for but to find out what's wrong you'll
have to open the back and do some checking with a multimeter, if you don't
know how to diagnose the problem you're probably better off to have an
appliance repairman come look at it. I would guess he'll replace the
thermostat or selector switch, but without a model number we have no clue
how the unit is setup.