Iphoto Faces photo recovery

Here is issue:

Friend used computer ( never again)

I opened Iphoto to find all the photos in the "Bar b q" event to have been replaced with Faces thumbnai
What would cause an event to show only faces thumbnails? - here is how its named 'CIMG5930_face0'

I somehow managed to return photos to full image but they are low resolution around 50 kb per photo

Is there a way to find the original photos on my mac? The photos wont revert to original , option greyed out.

Checked Trash, dont have originals backed up.
Iphoto 09 + OS X 10.5.8

Thanks Mat