Hi . the belt has either come off or split . its a rubber band that attaches from the motor to the brush and as the motor spins the band spin , so spinning the brush . if you have a local shop that sells Hoovers then they will be able to order it for you . it can also be ordered online . they can be a bit awkward to fit , so might be best to get someone in . but it shouldn't cost too much as the belts are cheap.