help drivers rear door locked

hi
my drivers side rear door has locked and will not open from inside or outside, will not unlock with the fob or the door release on the dash I tried to pull the lock button up with my fingers but even this didn't work as the button just shot back down. is there a easy fix not even worried about locking again but need the door to open ...

help ...lol

Can you open it at all, say using the internal handle on the door?
Is the child safety lock selected?
I presume that this is on your Disco 2, the door catches are prone to failure where they can't be unlocked, but they can often be opened using the inside handle.
Unfortunately, the usual way to fix the door latches is simply to replace them, they aren't really very easy to get into and as it says on most electronic kit these days, "No user serviceable parts inside"
Take a look at this:- http://www.discovery2.co.uk/Reardoor_lock.html
But if the child lock is selected then I don't know how you're going to proceed.