The automatic fuel filler door latch is broken on my '02 disco

What is your question?

the door wouldn't open when the interior switch was pushed, and in trying to open it (so i could fill up! lol), the plastic tab on the door itself came off. I have no idea how it fits back on, or whether it's been damaged (looks ok). That said if i could get it back on correctly the switch isn't working, how can i trouble shoot this problem so i can replace whatever needs replacing????