Check the fuses at the main fuse board, if those are ok check that the wall switch for the heater are on. If these are ok then turn off the wall switch, remove the heater dials from the top of the heater, remove the screws that hold the top cover on, you will most probably find that the fusable link has melted to prevent damage to you heater, replace the fuse, and, before you ask " where do I get them from" look on the internet, simples!
Alexandre Meerkat., February 2012