Okay ive given the same advice to people and it seemed to work a couple of times...my advice was dont talk to him txt him or anything ust act like you dont know him let him remember the sweet times you two had together he will eventually come back to you ...this worked for me and 2 of my friends
People always tell me to flirt with his best friends. Idk though. I think personally that if you want him back, then you should sexily flirt with him (but not obviously) and keep looking at him. Then when he begins to talk to you again, tell him that you sorta miss him. I haven't tried this but i'd give it a shot.