This evening mowing my field I accidentally ran over a old rope with my bush hog. The rope tangled around the blade shaft, rapidly slowing it down. I was able to disengage the pto and free the rope. But after I stopped and turned the tractor off it will not turn back on. I have never had any starting trouble it before and can not see why it won't start now. I check all the electrical connections and they seem fine. I would appreciate any advice out there. Thank You.