This is what it could be: Heater faulty - thermostat faulty - safety thermostat tripped - clogged with lint someplace - control module damaged. If you know an electrician he can maybe help you by testing the basic components. If not I guess you at the mercy of a domestic appliance engineer...we have living to make as well!
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix tumble dryers.