Mufi bro,
If u think or believe that she has some pheelings left for ya then do as Khan sab said,
but if you know or blv that she believes more to that "another guy" then it means her pheelings for ya was not/never strong enough,in that case forget her & move on.
ekta kotha achey na? jodi shey chole jay tahole bujhbe shey kokhona tomar chilona
Just a friendly advise.