One inside and one outside.
Mondeo central locking not working on one door.
If that fails the latch is busted.
Just google how to reprogram your mondeo remote.
If you have the remote get it programed if it doesn t work as every mondeo that ive had that has your problem works fine off the remote.
Is it connected still and last are both connected to the latch mechanism.
To test the wiring there are 3 wires in the plug 2 yellow and 1 black test between yellow and black and when the central locking is activated you should get 12v for abut 1 2 a second if not test between the other yellow and black 1 yellow is for locking the other yellow is for double locking if you get 12v then the wiring is ok.
Then look at the key lock cylinder.
So you pull the door card inside door covering and look at both locks the inside pull its it working.
There are 2 levers.
The central locking module in the drivers door is very common to fail on mondeos.