Defender TD5 2006 Gearbox/Transfer Box Problems

My 2006 Defender 110 TD5 has ended up stuck with the gear lever in 2nd (won't move at all) and the transmission apparently in neutral. Transfer box seems to me to be in neutral (not fully engaging either high or low range) but I wasn't actually driving it at the time, so not sure of the full sequence of events.

It had just been driven with the diff-lock on in low ratio in order to descend a steep slope with a loose gravel surface. Problems occured when back on better ground and removing the diff-lock, but, again, I wasn't driving so not completely sure.

Now in the garage and waiting for the bad news, but anyone got any experience of this?

depends on symptoms ,yoke grub screw under turret can come loose mean stick moves but gears arent selected , or selector pin on selector shaft can jump out of selector fork slot ,can be re-engaged if you know what your doing or may require box stripping