If you ask someone out and you were rejected and he started ignoring you afterwards how do you resolve the problems?
Try keeping a low profile for a while, and don't go out of your way to be where he is. He will be more put off if you hang around too much. Don't ignore him either - no need to play his game or give him reason to think you aren't nice to be around. If he feels like the pressure's off in a dating sense, he might thaw out a little. Getting rejected is sometimes a king-hit to your confidence, so take heart from the fact that it happens to almost everyone, even between people that eventually marry!