I had recently a similar problem and it turned out to be the brake light switch. This mechanism controls and prevents shifting out of parking without depressing brake pedal. Please check if the brake lights go on when you depress the brake pedal, if not and the bulbs are not burnt out it is most probably this switch. The switch is located just above the brake pedal, it is tricky to get to it as you may have to feel it running along the brake pedal shaft. In order to replace you must disconnect hardware switch and carefully rotate the switch out. The part itself is bought from your local Land Rover dealer should not be more than $60 USD, conversely you could buy a replacement at Autozone or your local parts distributor. Personally I'd recommend original. To install you must depress brake pedal and turn it into place, then connect harness.
Good Luck
newtest3
on the gear shifter
Put the key in the ignition in front of hand brake next to the gear shifter.
I run in Hi gear
Check to see if Brake lamps work when brake pedal is pressed. If not gear shifter is locked for safety so replace fuse or repair brake lamp switch.
Not really describing answer , but i would assume you shifter cables have broken
If a 1993 Land Rover Discovery is stuck in a low ratio gear, check the transmission fluid levels. If the fluid levels check out okay, the transmission may be experiencing a jammed gear.
For most newer model cars you need the key to change the gear.
Move the car at a walking pace, put the gearbox into neutral and move the high/ low stick from low to high.
80/90w gear oil
land rover discovery
shifter rod gear linkage
your shifter linkage is probably broken.