Check the wiring if it's a electronic door locks and inspect all wires to see if there are warped, bare, or damaged. If not then inspect the mechanics of device.
First try moving the door up and down while you try to unlock them-they may be getting hung up on the striker. If they are frozen or stuck, shoot some wd40 inside the lock. Then replace them once you get into the car.
Remove the door trim and panel. With the window up, lubricate all moving parts to the lock and hinges. Autopart stores also carry graphite lubricant for the inside lock assembly.
Go to your local police facility and get the name of a good car thief. Have him disable your door locks on all 4 doors. Since no one steals Land Rovers the locks are totally unnecessary,
Try wiggling the door locks, gently. Sometimes, door locks get jammed from regular use. If that doesn't work, then take it to a mechanic for further inspection. The cost should be minimal.
The only thing you can do is take off the door panel and repair or replace the lock aucuator. This part is usally what controls the door lock. Be carful with the door panel so nothing breaks.
Contact your dealer or local repair shop, as this involves getting into the door's interior area. If you want to attempt this yourself, refer to a do-it-yourself manual.