Break Ups and further difficulties?

My ex gf broke up with me a few months ago. We stayed in touch but then I walked away. Tried coming back for friendship that she wanted but now she is staying away altogether. Cannot get her out of my mind.grief and sorrow like you cannot believe. I know what I am supposed to do but doing it has been impossible. No friends or family here and the solitude is overbearing......what else can I do?