Need more info on what you have and what ios you are using. Ios 9 should have a recently deleted folder where you can recover the pics. A retore might bring them back if you have a recent copy.
What device are you using? If iPhone, did you check the Recently deleted album? If so, you can check on iCloud.com on Computer and see if they are backed up there. If so, you can restore with that back up and get them. Only way.
If you don't have duplicates saved elsewhere, consider the pics gone. If you have an iCloud account, login to iCloud and see if the pics are in your iCloud Photo Library. If so, enable iCloud Photo Library on your iPhone and allow the pics to sync to it.