i have had the problem so many times and it is in fact what was mentioned above, dirt gets into the return spring in that latch. Just take a flat blade screwdriver and scrap all of the dirt out of the latch area near spring and clean out as best as you can and spray some lube in there and work it back and forth to loosen it up and try to open and shut the hood a few times after it frees up some. Should be go to go after that.