Most Helpful Girl
Depends on the situation. Need more details
Most Helpful Guy
in general, go back in time, love lost is usually a point of no return.
if the feeling is mutual, play it off cool, then aproach her that you feel there is something missing in your life and you're sure that it was her love.
other then that, i wouldn't know how to help here, pretty litlle info to go on, like why did you guys split up in the first place?