If the fan and the light is comming on but theres no heat then its nearly always down to a faulty heater element.
If you empty the oven and from there remove the back panel inside the oven there you will see the heater element around the fan motor.
Inspect the heater element and sometimes you can see were it blows as you can see an actual blow mark on the heater.
You can replace the heater element from there.
So check that and see what you find as from the fault you describe its nearly always the heater element thats faulty if the fan and lights are comming on.
If you need anymore info just get back to me.
Its just called a heater element. The part number you need for the heater element is###-##-####/p>
Just google the part number and they will all come up from there.