The one friend who entered your life,changed it a bit,then vanished.
What remains becomes the building blocks for your future,one that can look back the past failures.
Never forget that friend,even in the day and age of technological connections,and who knows?,they might just return one day.
This is a fairly common-ish theme,and how it progresses from that end point is anyones' guess.
She may come back herself,she may send a letter stating what happened,she might even show up in a newspaper(for better or worse),and/or she may never return.
However,one path is to become super famous and use that influence to seek her out,and with your fame spread around,there's no way she wouldn't have heard you,except in the most dire of situations.
The past is set,the present has options,and the future is yours to carve.