My B21 gear shift was stuck in M but in neutral position. it would start and run in that position. I got the mechanism to go back into the proper position and it now shifts but will not turn over. Any help would be greatly appreciated.
Have you looked at the linkage? Do you have a WSM?
Seems that when it indicated it was in gear, it was in neutral. So, changing nothing else, "persuading" it to indicate neutral prolly put it into gear. I expect that your starter isn't strong enough to turn over the engine and roll the tractor as well. If you can determine whether it's in forward or reverse, and push the machine while trying the starter, it may start. But...
ShaunBlake,
unfortunately I do not have a wsm. It is hydrostatic drive, with the clutch I don't know why would it be trying to move the tractor. There is no indication that it is trying to turn the engine, no dimming of indicator lights, no sound of any kind.