There will be a heating element - a fan will blow air over the element to make warm air - a thermistor in the airflow will provide heat information to the control board - there may even be a thermal cut out (thermal fuse) as a safety measure against overheat.
The element may be defective
The fan may not be working
The thermistor may be defective
The control; board may be broken
The thermal cut out may have operated
Your appliance engineer will know better than I do and will soon sort you out - my answer here is all guesswork. The most probable cause is likely to be the element.
Good luck...
Peccavi
November 2009
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix tumble dryers.