When you have an ex boyfriend to get back you will do crazy, out of character things to make them love you again. You may call and text him incessantly letting him know just how much you are thinking about him or you may be trying the opposite by giving him the cold shoulder until he can't stand living without your attention any more. Think calming and clearly about the situation. If what you were doing is working, you'd already be back together. It is time to re-evaluate and re-strategize your plan of attack.
Consider the way your ex boyfriend might perceive your actions. If you are contacting him too frequently or showing up at all his usual haunts, he may begin to see you as desperate and needy rather than the wonderful woman that you are. Instead, maintain your distance for awhile, if you bump into him or he gives you a call, be polite and congenial. Make him remember all the reasons that you are a great person, this will give him enough space and breathing room to begin to miss you. After a few weeks, if you haven't spoken to him you can give him a call and just ask how he is doing. Don't try to start a big conversation, but hint that you miss him.
Begin to pick up the activities that you liked to do but didn't have time for when you were in a relationship, and play the field. Go on dates, go out with your friends. All these activities will make for a more interesting conversation the next time you speak to your ex and will illustrate to him that you have a life outside of him that is stimulating and exciting.
Hearing about all the fun and interesting things you have devoted your energies to will make him remember that he wants to be a part of that, or at least marvel at how independent and emotionally stable you are. Stay collected and remember to work on yourself during this time- pursue the things that interest you and engage in activities that exercise your talents. Regardless of whether or not you end up back together with your ex boyfriend, pursuing hobbies rather than him will leave you more satisfied regardless of the outcome.