Water damage on wood? Is it flooring, ceiling, furniture? Each treated differently. Ask in a sentence or two what you hope to do.
Is the water damage on a piece of furniture or a door, or what? You might be able to sand the wood down well and then restain or repaint.
I am not quite sure what was damaged, how much damage, but here are some links you might look at. Good luck.
Need more information please.
Sand it down and then varnish it
Where is it, is it a structural area?
Can you post a photo?
For small areas that were non structural- Ive used the Oatey putty stick.
Other times we have chiseled out the defective damaged wood and a replacement was placed primed caulked and painted.