Could be many things and depends very much on the vehicle.
The transmission is broken. Take it to a shop.
Is there park and nurtural?
i would think it's a syncronizer inside the transmission
What would cause the 1995 Nissan Pathfinder not to go in forward or reverse?
Had similar problem, was rear brake shoes. They automatically adjust in reverse and after short distance would lock on.
the only problem that you can repair yourself would be with the linkage. but if all other gears work except reverse then the problem is probably internal and should be inspected by a professional. it makes a big difference if the trans. is manual or automatic also.
Automatic or manual?
The reverse wire on the side of trans mite have came off or you may have afalty reverse switch on trans or a bad ground from bolbes.
auto trans fluid its crazy i know
It would have a sm 465. Its a heavy cast unit with low (granny gear) and three other forward gears plus reverse.
If you have the manual transmission 5 forward and one reverse, add to that 4 wheel high, 4 wheel low, and 2 wheel low, and I guess it would all add up to 24. But 5 forward and one reverse with a 4 position transfer case is probably what you are looking for.
the letter d