A while back i meet this girl and we started to get to know each other and then we started to flirt then she was in a relationship but we still kept in touch and flirted with each other but now that shes isn't in a relationship, all of sudden she's ignored me and wound reply to me.

what do i do or how do i get her attention back?

Mate I know a lot of women like this... they have real "close guy mates", when a lot of the time they are either used as weapons against their partner to make them jealous, or are "life boats" so they can just go ahead and sleep with them after a bad break-up...

Now your post doesn't tell me much about your relationship dynamics but did you become at all needy when you realised she was single? trying to get her on a date or back to yours desperately? That can instantly put a woman off if you're easy.

Another thing I will say is that some women purely like to string men along, always hanging sex in front of them but never letting them push past the friend boundary, this is purely because women in general crave... in fact need... male attention. Having you there probably makes her feel wanted, like you're always there if she wants you. I know a few girls like this...

My friend... there is a good chance you are pussy whipped without actually ever attaining the pussy, I hope I'm wrong, but my advice is to stop talking to her... especially if you talk to her often, if you suddenly start acting distance, it is possible you can have her running after you...

But again I don't know much about the situation so good luck!

Also will add you are suffering from what a lot of people on this forum would call 'ONE-ITIS'... forget her mate, if you don't have other girls in your life go get some...