Front porch has old tongue and groove flooring. The nails at the end of the boards have come loose and two boards have buckled. What’s the best way to go about resetting them? I hate to cut away the tongue since that helps to keep the boards locked in, but it looks like that’s what I may have to do.
Just align everything and tap it back into place with a block of wood laid over the top. Work slowly and watch for misalignment, working from the end that's still in place.
It should go back in without much trouble unless it buckled because of severe swelling due to moisture. In that case, wait until it dries out and try then.
I'd use galvanized, coated, or stainless steel trim-head screws to re-fasten. Nails may not hold well in that old framing. Screws with pilot-points will help prevent splitting.