Love your ex

The guy I like is my ex. It didn't work out the first time and we were together for 8 months. Im not really sure exactly what happened. But we both moved on and the guy I had broke up with me. He is still with his girl, and we haven't talked since we broke up and we've been broken up for 3 months. I want to talk to him. Can you please tell me how? I've tried emailing him but he wouldn't email back...