Could be that the belt has broken.
Historically, there's been a lot of problems with overheating of dryers which subsequently caught fire as lint had got to the elements.
Have you checked yours against this?
Whirlpool has issued an urgent appeal for owners of dangerous faulty tumble dryers that have not yet been replaced or modified to come forward.
inews.co.uk
You might be entitled to a replacement.
If not, changing a belt is possible but it is a bit fiddly if you don't have much DIY experience.