Camera roll lost everytime my iphone restart?

I had my phone battery died once and checked my photos and they were gone. I tried taking a photo after and restart again and the new photo will be gone again.
I tried checking the dcim folder in my iphone and it is blank and i have no back up of my newest photos.
Is there anyway to retrieve these pictures? Or are they gone for good? Also why is this happening?
I have iphone 3gs jailbroken with redsn0w 5.1.1, my sister also has the same problem with her ipod touch 4.

Well these type of issues are usually caused if you jailbreak your iPhone or iPod. Best possible solution to avoid this problem in future is to restore it to factory through iTunes. It would solve all such problems. Cheers!