Sometimes I can take videos, but not photos. Blank screen comes up when I choose Photo. Also, I have lost the most recent photos that I was able to take.
1. Go to Settings→ General→ Reset, then select "Reset All Settings".
2. Make sure you're not covering the lens when you take the photos
3. Restore your device and set it up as new.
4. Make a Genius Bar appointment with the nearest Apple Store to have them diagnose the problem.