what do I do if I want my ex-boyfriend back?
It really depends on the situation, like what happened between you two. And in a previous question you said that he's already moved on... which will make it that much harder. If the break up was your fault, explain to him what happened and everything. If he break-up was his fault, let him go. Sometimes the pain caused during a break-up makes you want the person back, which isn't always a good idea. Stay strong.
you should leave it alone and find somebody else theres a lot of guys in this world so start looking dont pick the TRASH YOU THREW AWAY!!!