how to fix a broken bonnet?

Focus zetec 2008 1.6 diesel
Removed front grill to work on Closed bonnet wheel away from car, returned to find that the key no longer operates to open the bonnet It turns with no resistance, I do not recal using force to take the grill out and the lock looks ok, Iv tried pushing, Pulling, even gently twisting the cable and applying pressure to the white plastic coupling while turning the key but nothing, can you offer advice on how to repair, or how to open the bonnet,
Thanks
Phil