Photos Faces

So suddenly all my labeled faces (over 6 years worth) which had shown up fine after the iPhoto import now weeks later have suddenly disappeared. What I mean is all the people show up on the initial screen, but there are no photos when you click on a face. If I add new photos and manually type in the person's name that picture will show up under that person's name under faces but not the 1000s of previous ones. I go to old photos individually and they still appear to be labeled correctly, but they don't show up in the faces section.