You can try talking to him and tell him how you feel. If you do, and he still doesn't want you back, i think it's time to call it a date and just move on. I agree, it depends who broke up with who, and for what reasons.
And BE 110% SURE THAT YOU REALLY DO WANT HIM BACK. :)
Depends on why the relationship ended and who broke up with you. If he ended it doll, why even bother. You deserve someone better than that who actually cares about you. Relationships and heartbreak are a part of life and growing, youll find someone new and better.
Try to negotiate on the issues that split you up if you can. And if you can't, that's probably a sign you should move on.