Find a way to get some internet contact of her. I got the email of my last oneitis by saying her I would send her an musical album I was about to release for her to tell me what she thinks of it. Then I sent the album, which contained a song for her (which I told her) plus my confession.
Got ignored, got her Whatsapp contact through an acquaintance after that, insisted for a response and got ignored again. She told me "response to what?". I told her "to the things I sent you, didn't you get it"? She told me she has gotten ii, yeah, but didn't respond anymore.
But it worked to forget her.