Is it possible to retrieve pictures from a deleted saved photos folder on a Nokia Lumia 521WP8?

Question

I accidentally deleted the entire 'saved photos' folder on my Nokia Lumia 521 WP8. The pictures were not saved to Skydive and I do not have a memory card installed, so the pictures lost were stored only on the phone memory. This happened once before shortly after I purchased this phone but at that time the pictures I lost were not of great importance so I did not go out of my way to attempt to retrieve them. This time a few of the pictures, specifically those of my girlfriends 4 year old, were very important to me. It seems doubtful but if the pictures can be retrieved please explain to procedure. Thank you in advance for your assistance. I will save the pictures to Skydive and/or purchase a memory card in the future ☹