Depends on the severity.  Now a failed test, that usually doesn't last for long.  I usually give it 5 mins tops 

  But for relationships, depending on how close you were to the woman, err, or man, give it some time.  Maybe you could try "getting ON" something, or 
someone.
I don't know it's possible to be 100% OVER anything.  There's always those little remnants of memories lying dormant, haunting you whenever they feel up to it.