GRRRRRR....broken drive sprocket....

my auto-bike has 2 sprockets on one side of the back wheel both of them in a format similar to the way a regular bike with caliper brakes can pedal backwardswith no affect on the momentum of the bike. the large sprocket responsible for the motorized propulsion of the bike is now spinning freely in both directions.the bike is one of those schwinn windjammer folding yacht bike originally it had a 33cc engine and was built with 25 mph in mind...(would going 35-40mph cause too much wear on siad mechanism btw) any suggestions?
requards,
guero loco

just keeping this up on the front page i still need a lil help with figuring this out

its a schwinn windjammer with a wheel from dih long co. or at least thats the manufacture of the back wheel from what i gather but i cant find a replacement