Do I have a blown engine?

My lawn mower engine stalled while mowing grass. I can turn the flywheel but it will only spin to just about 1 complete turn. Then the flywheel stops like it is hitting something and will turn no more. I can turn the flywheel the reverse direction and it stops just before turning around all the way. It seems to be a intenal problem or maybe it something simple I'm missing. craftman model#917.252531, 15.0 hp . engine model no.-283707, type no. 0217-01