Hi Judy,
It is very common for Tumble Dryers to fail in this way and it is normally their Thermostats that are the cause. They are very easy to replace and buying them from the internet is easy too (you'll need the make and model number of your machine). Normally a pair of Thermostats cost around £20 (you replace them in pairs as it's common to have 1 cold and 1 hot type on the same machine).
There aren't many parts on a tumble dryer so dismantling them is straightforward... don't be afraid to try! Usually, you remove the top lid and rear cover at which point the Thermostats are either then in view (2 wires to each of them) or they're under a cover which you'll have to remove too.
The wires connections just pull-off the old Thermostats and push onto the new Thermostats once you've unscrewed them from the machine.
I hope this helps.
Barry, November 2010
