nailingnailswood
As seen in picture, one of the pieces of wood is sticking up. The top panels are secured by nails that go through the perpendicular supports. I tried hammer the top of this wood panel back into the nail with no success. Then I tried just hammer up the entire piece so I can remove this nail but the other nails that secure this piece to the perpendicular supports are not budging. The nails from the bottom are embedded to deep to try to pull out too. Any ideas?
Another method is to get pliers and a block of wood about the height of the extended nail ( protruding out the wood). Grab the nail out the side of the pliers and insert the block of wood between the joist and the head of the pliers. then use the leverage to pull the nail out, this is also great because it will not damage your wood.
I think what you need is a Palm Nailer. You can get these in air or electric powered versions. They are compact and are handy to drive nails in tight spaces.
Best Answer
The chances are you are not unwarping the board. You can try but its been there a while and will probably go back. I would hit the really high point with a planer, get it close to even then sand (for a while) this thing flat. Yes it will take some labor time but the alternative of trying to make this straight will take far longer and probably not work.