Why my guy friend ghosted me all of a sudden?

My only guy friend started ignore me and stop talking to me with no reason but he stares at me every time that we are in near distance. We had a really great time together, the same sense of humor and I'm sure he appreciated our friendship. Few days ago I asked him something, he was pretty fine and continue the conversation but today at school it was the same. I dunno what to do.
Why my guy friend ghosted me all of a sudden?
Post Opinion