I guess...
The most common problem is usually the power cord - it gets stressed as you pull on it during normal use over the years and the connections at one end or the other become detached.
If there's a fuse in the system it may have blown - UK plugs have fuses in them @12A I guess you're in 120V land.
The on/off control switch may be defective
A wire may be detached inside the machine (very unlikely)
The motor may have failed but you usually get warning that this is about to happen from strange noises, sparks and smells before it dies.
Keep the wheels of industry and commerce turning and buy a new one. Have it repaired by a specialist ($$$) or tinker with it yourself at your leisure.
Good luck...
Peccavi
March 2009