Do NOT write anything to the drive. Let's hope that you store your
data on another drive aside from C: cause there's no way to shut down
the system without writing to the C: drive. Any newly written file will
use space that is now flagged as free, and chances are very good that
it will overwrite your picture files.
So...presuming that you can keep the drive intact, you can search for
file recovery programs. The ones that I know of are not free, but use
them as a starting point for Google searches:
Ontrack Easy Recovery Pro
Get Data Back by http://www.runtime.org
I've used Ontrack to do similar things with a crashed drive. Also be
aware that you cannot write the recovery data back to the same drive.
You need to have enough space available on another drive.