1999 drivers door cable has broke is it a easy repair ?

Yes but the genuine cables are seriously daft money for what they are.

Do you mean door latch cable? How can you tell it's the cable and not the door latch? Have you taken the door card apart? Can the door still be opened? What are the symptoms? Much easier to do if door can still be opened than if the door is blocked. Cables are not so expensive. Island 4x4 lists them. Latches are quite expensive. On rangerovers.net you will find the procedure (with pictures) for how to change the latch. Have a look it might help.