How can you get your boyfriend of 9 years back after he moves out?

A lot can happen in 9 years and you didn't mention if he had a girlfriend or was married with children. I have a feeling he is at least married, so I'd let it go and move on with your own life. If he is single, was married and is divorced and if you've been in touch then that's a different story and you can try getting together for a few days.