How to get your ex to be your friend?

Well, there's this guy that I dated a year ago. Our break up was kind of messy, I told him that we should just be strangers, because I couldn't be just friends with him but I didn't trust him enough to continue dating. So this year, I realize he goes to my school and I see him around quite a bit. Everytime I walk past him and his friends they stare at me and the get a little quieter I guess. I walk past him in the hallway a lot and he looks at me then looks away. I tried to make conversation by making eye contact and smiling but he kept walking. I kind of want to be friends again with him and reconnect, but I don't know how. I'm not sure if he hates me or what. His friends think I'm pretty, but I don't know what he thinks of me. Please give me some advice on how I can get him to be my friend or just talk to him in general. Thank you!!!!