Black Decker bench grinder/I need help getting it going

[Triphammer]

Hi, just picked up a B&D bench grinder/sander. I turned it on when I got home and it worked fine. When I went to use it today, the wheels did not spin but it made a humming sound. Helping the wheel by hand spinning it did not get it going. Anyone know what I can do to repair it? Where to get parts?
Thank you very much for your help, I really need to get this thing going.