Hi I have a 2000(w) vauxhall vectra and the central locking won't work using the key fob or just using the key in the door. Ive changed the battery and still no joy any ideas

You say, "You've changed the battery..."
The fob battery? You may have a programming problem with the fob but you need to find out why it won't work from the door.
Check all the actual lock/unlock functions to be sure a lock actuator isn't causing problems. And check to make certain all the vehicle's fuses are good.
Your local dealer or a shop experienced with automotive electrical systems should be your next stop.

I am guessing you are in the UK, take it to Halfords, they can check stuff for nothing. However, they will try and sell you the part required.