I have a Land Rover it starts but when I want to move it?

I think you need a new gear-box sorry

No check the brake light switch or brake pedal some of these vehicle have a electronic lock fitted to gear shift

Make sure it has enough brake fluid, then check all fuses.

refering to short lever?
its function is to engage low or hi gear and on most models a left and right function engage a differential lock.

transmission in neutral and 0-3 mph to move shifter

The car needs to be stationary !

would advise against trying to bypass park switch try ajusting first

hi centa, sounds to me like the brake release on the gear selector, when you put your foot on the brake it releases the gear selector peg so you move the gear selector, if you can remove the top cover have a look down and see if you can see the lock peg moving, if it is, it sounds to be more like an internal problem. hope it is something simple.

have you checked the oil level?  When is the last time you changed the oil? 

check the fuse box under the seat.....i forget with fuse it is but if its missing or blown......the truck will not move...happen to m e