if you get really desperate you can try to roll it on. Put the chain back together and take it off one of the sprokets and have it all the way around the other, the one thats off try to get it catch on a tooth or two and push it back or fowards which ever way to try to do it and try to have the wheels spin the chain onto the sproket. But i woundnt recomend this cause you could break a tooth or the chain it self, but like i said if you get desperate...