How do I restore Default account pictures in system preferences?

After my school re-imaged my mac to their altered mac os x which has a LOT of flaws, the defaults under profile pictures says No Items.

How can I fix this when you can find them in the Macintosh HD library?

They all have the pictures inside

I hate my school, for their altered Mac OS x that is supposedly a policy backed must re-image version in order to use a our macs at school... ********...