A T20 is a star shaped tool best going to b and q to buy one only a couple of quid. When you remove the cover you will see an impeler and there is usually something stuck there to stop it turning.
If it is not pumping the water out there may be a blockage in the pump drain which is accessable from inside the appliance through the pump cover.This can be found in the instructions.Usually requires aT20 to remove the pump cover.
If the belt has not come off then you will find there is a problem with the motor brushes. Quite a cheap repair if you know what you are doing as the brushes are readily available.