Guys
When I bought my 94 disco it came with various problems. The mechanical stuff such as new calipers, rear shocks and welding have now all been done. It has 2 odd keys, 1 for passenger door and ignition, 1 for drivers door and neither fit the back door. There is no fob and none of the keys activate the central locking. Have done search on previous threads but cannot find anything that matches my problem(s).

The main question is, where do I start to try and sort this out??

Get the central-locking working via the lock in the drivers door, or better still use a fob and the you will only need the ignition key.

U will have to find out why the central-locking isn't working, as it should work on the key or fob, check that you have the alarm/centrol locking ecu first, then that the micro switch on the back of the drivers door lock is working.

U could forget the above an install a 3rd party remote alarm/central-locking system, loads of kits on e-bay.

sounds like various locks have been replaced with the passenger door and igniition being origionals.

id look on fleabay for a set of lock barrels and replace the door locks so they are all the same, personally i wouldnt bother changing the ignition lock.. but i havnt looked to see how easy it is. if the central locking can be got working off the door locks thats a bonus but remote locking off a fob is just more fiddly batteries to go flat.. and alarms are a pain in the butt

It sounds like he drivers lock has been changed so it could be that the central locking switch hasnt been fitted back if it has central locking fitted.
You can buy locks made to key number from the dealers for not too much money.
As for the rear door it could just be siezed up due to lack off use.

You could fit a non genuine remote locking kit which you can get for less than £40 inc motors.