Guard Byron:
Aren't you the person that left with the pure white fairy stone to meet a fairy? What...?! Looking at you, it appears that you had a fight in the valley. Did you lose the pure white fairy stone? Oh, that's really too bad...
If you still want to meet a fairy, then you'll just have to make another fairy stone. Did you make the last fairy stone by asking for wisdom from Sage Cronos? You'll have to go back to him and ask again.