They have two elements in them, one for the dryer, one for the washer.
On a lot of machines you can see the casing for the dryer element by taking the top off, the element will be in a largish box covered in silver heat insulation.
If you have the equipment you can check the resistance across the element, if it's open circuit it's failed, if the element is ok then it will probably be a thermostat or a TOC which can also be tested.
If you are not sure about doing anything yourself call someone in though.