A feature in the iPhone's iOS 8 software lets you browse photos you've recently deleted and retrieve them, putting the images back into your main photo album. The iPhone keeps deleted pictures for 30 days in the Deleted Images folder, after which time they are removed from the phone automatically and permanently.
Tap the Photos app to start it.
Locate the Recently Deleted folder. Tap the folder to open it.
Scroll through the recently deleted images and locate the one you want to recover.
Tap the image to select it.
Tap Recover to retrieve the image from the Deleted Images folder. The iPhone prompts you to Recover Photo or Cancel.
Tap Recover Photo to restore the image to the Camera Roll folder.