Apparently you don't have that person's information. I'll assume you have tried tracking the person down on social networks, any gaming forums (just for example) that you know they at least used to hang around on, and the like, and have come up empty.
Has your information changed? If that person wanted to contact you, could she? There are supposedly ways to suggest thoughts to another person, but don't quote me on that.
If you had parted on bad terms, a honey jar may help along with other methods.