Unfortunately there is not much you can do to get your boyfriend to break up with your best friend and come back to you as he has made his choice. Time may be the healer and he may realize he does love you, but there is always that risk he will either stay with your best friend or possibly break up with her and meet another girl.
well you cant just say i want you back it would be 2 awkward so try flirting A LITTLE then act as if nothing happened after a while do the thing u use to do to flirt if you guys are still really...
The main thing is whether she wants to come back to you or not. A good talk between the two of you is desirable to clear things up, and if she states that she wants to stay with your friend, then...
Well if you like your friends ex DON'T that breaks girl code especially if the relationship just ended. This could start issues and possibly end a friendship.