Hi Suzanne, there could be 3 reasons.
1 x the heater element could be open circuit.
2 x the reset stat behind the heater(white with red button) may need resetting.Just press the red button and it resets.
3 x PCB in the door controls the heater,it could be that the pcb is broken internally so not turning the element on. Hope this helps in some way.
All the best.
Foxy
July 2008