Well if you traveled back in time you technically shouldn't exist either. But if you already do exist, then your parents not existing won't have any effect on your present existence since they already don't exist in the period you exist.I wouldn't go back and change anything, simple reason being that one little change might alter the flow of history significantly enough to prevent my parents ever being born, which means I wouldn't exist, which means I couldn't have travelled back in time in the first place, which leads to a paradox and a headache.