I am just obsessed with a girl?

I like one girl madly. I never talked to her but like her .After five years I just found her agin . But the problem is that she is not intrested in me. But how to erase her from my mind I am totally obsessed with that girl . I tried to forget her from last five years . But not able to do that. Can,t think of any other girl except her . How to make friendship with that girl . My bad luck is always with me now I am in different country. How to be her friend from different country. I tried to sent her friend request in facebook but she declined. Plz help me what to do .