There's this guy, Who seemed to like me for months now, I'd always catch him staring and me & smiling, I was Interested in him, so I finally got the courage to smile back and he approached me, asked me about myself, what I do for fun. Then he went cold and started ignoring me, & he forgot my last name, so I was hurt & decided to move on, now I catch him again staring at me, no smile. What do you think he's acting this way for?
Just test the waters to see if he will take the plunge. How? Walk by him and purposely drop you cell phone or wallet. See if he picks it up like a gentleman. If not, go smile to another man with manners!
Some guys will actually play the hot then cold game as a frustrating way of flirting. Some girls do this too. The other reason a guy would do this is if you unintentionally gave him a bad vibe when he initially approached. You may have been nervous and perhaps a bit standoffish, which is completely normal but it may have discouraged him. He is likely still interested but trying to gauge your interest in him. Be as open and friendly with him as you can next time. Don't be afraid to approach him. Good luck!