Only if you have a backup, to restore from your camera roll, that contains the deleted photos for iPhone 4s. Otherwise, they are gone.
The iPhone camera roll is not designed for photo storage. These photos should be regularly imported to your computer, just like photos from any digital camera. If you want photos on your iPhone, sync them to your phone.
Know more about
recovering iPhone photos easily, please kick the below site.
MyJad Software - iPhone/Android Data Recovery, iTunes Backup Extractor