Just a shot in the dark, but common enough - is it possible the latch
snapped closed when the hood was open so the hood can't engage the catch? If
so, having somebody hold the release while you snap it back open with a
screwdriver will fix it. Looking at how the latch catches the catch bar on
the hood should make it pretty obvious. If it isn't that, you can cycle the
latch by pressing down in the latch with a screwdriver and then releasing it
as described. Sometimes these things just get out of whack.

My other thought is that something on top of the engine compartment may be
preventing the hood from closing all the way. Of course, I've never done
that... <8^P

Mike