I'm going to use a bit of an analogy here so please bear with me as I paint the picture. Winning is like figuring in a competition. You can't win something you didn't fight or work so hard for, right? So if you want to win your ex-boyfriend back (read: heart, mind and soul), you have to dedicate your full and concerted effort to the task. And there are a lot of things that you have to do if you're absolutely sure you want him back again. And each of them will require a full commitment from you.
Start to win your ex back by putting yourself together. I mean, you've got to have your head in gear and get your emotions in check in order to pull this off properly and successfully. It won't do you well if you come up to him all messed-up and in shambles. You have to show him that you're a great woman in your own right and not a loser without him. Although you may be tempted, do not call, message, or contact him until you're ready to make a move. Remember that you have to look every inch beautiful and composed when you finally have the chance to meet up with him again so invest some time and energy on yourself and getting your house in order.
Once you're in the right elements for rekindling a lost romance, that's when you begin to gradually open up your whole heart to him. Be forthright and tell him what you wanted but do it with class and a sense of style without sounding or appearing to be too needy or desperate. It is very important that you make your boyfriend want you back of his own accord. Threats, duress and coercion have no place for relationship longevity here. Don't forget that love is a two-way street. You can't love your boyfriend and begin again without him loving you back. At the end of the day, it is still his call as to whether he'll take you back or not. So be prepared in the event it doesn't all quite turn out exactly to plan on the first encounter after the initial split.
So no matter what happens, you have to be a woman of self-worth, substance and dignity. Love and respect yourself in the same way that you love your ex-boyfriends. If you do that, then the right man for you would eventually come along. You don't have to focus all your life in pursuing your ex-boyfriend if he thinks or believes that the old relationship is over and done with. You can do everything within your power and grasp in an effort to show you know how to win him back. But if the odds simply turn against you, know when to stop, withdraw with no malice, retain your dignity and carry on with your life regardless.