What does this mean?

Most likely, he assumes you were asking his advice, so you could use his method to tell someone else you liked them. This is one of those places where tact might have helped. You best bet is to make the investment of finding a way, he will accept, of letting him know you were wanting to tell him, but didn't know how. Be honest. If you were afraid of rejection, say so. Whatever the cause of your hesitancy, include it in your explanation. It might be worth it to let him know in person, or at least by voice, rather than email.

Ouch. A possibility is he must have liked you and the moment he thought you were interested in someone else, he just decided, ok I am just a friend to her. Time to stop talking to her. Bye.

If I feel something for a girl, I can never just be friends with her. It hurts me and it will make her uncomfortable.

Some guys don't mind, they are hurting inside yet they go on and be the nice friend hoping one day the girl will change her mind and they just hurt hurt hurt. And the girl does not realize.

Tell him you were talking about him, because he thinks it's another guy. Go under a different name online and tell him "WTF! I was talking about you!"

Sounds to me like he thought you meant someone else, and his ego was S-H-O-T down. That's what I would think if it happened to me. About talking to him again, how long ago did this happen? If it was recent, give him some time. If not, and you don't have any way of getting contact with him, that sucks, I know the feeling, but I'd just see if he finds you again.