What happened with the case where it had a girl who suffered from some memory loss disease and she was extremely close to this teacher that she had when she was in her teens or something (she lived in NYC or some big city) and several years later the teacher saw her on the street and asked her if she remembered her and the girl replied with no that she doesnt know her at all and then she ws on Unsolved Mysteries looking for her.

Anybody know if they were reunited?

I remember which case you're referring to and as far as I know, there hasn't been an update. It's definitely a sweet case and I hope that one day they'll be reunited.

Then again, maybe they have reunited but UM just hasn't been informed about it. Who knows.