take the back pannels off and in the one you will see the heater take it off the pannel at the top there is two round things that look like watch batteries these are the thermostats on the back off them(the black side) you will see the one has a little hole in it push a neddle or something small enough into the hole you should hear a click this should of reset the thermostat and hey presto it should heat up again
hope this helps
simon
September 2010