TailGate Quit

I have a 2000 Chevy Silverado and the other day I went out to put something in it when the tailgate wouldn't open. I pull the latch and it seems to release a little bit because when I push back on it, it seems to lock back into place but it doesn't lower one bit. I had no warning preceding this and it doesn't appear that the cables are bad. Is this a common problem and what's the fix?

Thanks,

Jeff