How to diminish the appearance of a stain on hardwood floor?
A few years ago, some liquid (red wine or water from a plant) leaked on my hardwood floor (cherry). It took several months before we noticed it because it was under a carpet. This little incident left us with a very dark (almost black) stain of 4" in diameter (spawning across 3 planks).
Is there something I can use to diminish the appearance of the stain? Can I use some kind of bleach?
I would carefully try some oxygen bleach. By carefully, I mean not very long. Its not that caustic. If it looks like its going in the right direction, go a little longer. The kind I use is called StainSolver. The manufacturer recommends it for decks. You can find it with Google.
I don't know if there's anything you can apply to the wood to restore it - I'd doubt it.
Your options at this point would be replacing the planks, sanding & refinishing the existing wood, or covering it up with a carpet :)
How To Sand & Refinish Hardwood Floors