Guy I Used 2 Like

I liked this guy 4 a while and he said he was my friend. Then on AIM he blocks me so i get pisted and watever i stop liking him. He graduated and the gradutes leave earlier then us other ppl. So then some of the graduates come back 2 help the teachers pack 4 the end of the school year. He comes back and the whole day hes checking me out and laughing nervously around me. So the guy i liked that hated me that now i dont care about him cuz i dont like him likes me. So if he asks me out wat should i say no or giv him a chance? Guys r so confusing some times. If u hav an answer plz leave a comment thnx!