My "friend" is ignoring me.

[Gaijin]

You can't do anything alone...
You both need to talk about the situation, because the most times, both sides think the same way, but don't want to be the first who talks, or think they know what and how you think.
So, try to talk to him about that, if he refuses then obviously he doesn't care anymore and so shouldn't you IMO.
As said, sometimes you just need to force your friends to answer to your questions. If he is your real friend he should be real enough to tell you what happend or why he's acting like that.
Anything other simply means, he just don't won't you as a friend anymore, sorry but it's how it is.

I had many of such situations and most have ended good or with a fist fight and after that we were all good.
But as said my friends talked about that, they had no choice...