I dont know what to do....i cant walk away :[?

ok so this guy i like hates me, im like positive. im pretty sure he blocked me on aim, (cuz when my freinds say they're talking to him on my thing it doesnt say he's on, and i know i have the right sn), and he ignores me but i still like him! and i dont understand how i can like a guy like that. and this guy always switches around who he likes so i KNOW he's not good for me but i just cant stop liking him....and i just dont know what to do anymore. i try to act like a friend, because that would be better than him not talking to me at all, but i guess he doesnt wanna be mine...idk. so any tips on how to get him out of my mind or make friends with him. plz! i really need help.