Linda,
Could be either your drive belt is broken, or the carbon brushes are worn down on the motor. In both cases you will have to switch off the power at the socket before removing back panel, if belt is broken you can get a new one from a local stockist. You will have to slacken off the motor to allow replacement of new belt, then adjust to tension and tighten nuts to secure motor. If it's the carbon brushes you have to remove motor which is secured with 4 nuts, normally small screws hold these brushes in place which have a spring, if you prefer you could take the motor to local stockist who would probably change them for you approx £30 all in.
Good luck
Brian L, April 2008
