Aw, I feel for you! Maybe not that long but... anyways look at the bright side. you're single! flirt with anyone you want! think of all the bad things about them (mean ik) think of why this is better...
Ask him if he still loves you. if he doesn't then move on why should you love him when he doesn't care for you? there's probably a boy out there dying to be yours.
You should go oput there and find someone that loves you for you and you love just as much as he does. Loosing someone is always hard but still you should not let it show especially around the guy so...
You have to take a long walk and think about why you broke up with him. If he was disrespectful to you; perhaps cheating on you or you argued too much then these are reasons a relationship won't...
You simply contact them and strike up a conversation - maybe start simple with a coffee or lunch. If they are previously engaged in a relationship then its best to not do so.