First, as pointed out, the handle on the A post in the car should be pointed up in order to latch/unlatch the bonnet. Note there's a cutout in the chrome plate to match the handle. If all that is lined up ok and the handle refuses to move then my next step would be to unhook the latch from the rod on the engine side of the firewall. Then, does the latch move freely or is it stuck/stiff. Does the rod and handle no move easily?? There really isn't much to the whole thing, the handle attaches by two screws through the A post and the rod threads into the end of the handle, not much to go wrong other than dirt/rust possibly gumming up the handl sliding through the chrome plate or the same for the latch assembly. To be bent enough to cause it not to move would be very noticeable, so I' guess that it's a problem. Anyway try to isolate the problem component, and I'd bet a disassembly and cleaning will fix it up.