Accidentally did the factory reset on iPhone?

I accidentally did the factory reset on my iPhone 4s and it wasn't backed up! I lost all my wonderful pictures. I had 400:'( is there any way I can undo this? Please please help! 5 stars to whoever helps me and it works! Please! I understand they are just pictures but I had special ones on there. It's not on iCloud or my computer.

If you had "My Photo Stream" turned on, and you have other Apple devices associated with your password, there's a chance you could recover your pictures. Otherwise, I'm afraid you're out of luck. Sorry you lost your pics.