I have a 240 massey ferguson desiel tractor, recently not going into any forward gear, and crashing in reverse.It is not a shifter, but the levers are at the top of the transmission.
The fork inside your transmission is stuck somehow, unfortunately u are going to have to lift the upper transmission cover and see why that fork is stuck.You may be lucky and only have to pry the fork out of the reverse gear, but you may be unlucky and have to split it, but either way you will have to open the transmission top cover.