How to Rotate Photos on an iPhone
The iPhone lets you look at your photos any way you want to. Not only can you look at the photos on your iPhone in regular format, but also in a landscape view. Landscape view works best for photos taken in widescreen format, but can also be used on non-widescreen photos. When you look at a non-widescreen photo in landscape view, it will appear much smaller than when you look at it in the regular view.
Tap the "Photos" icon from the Home screen on your iPhone to open the Photos application.
Tap "Camera Roll" or "Photo Library" to find the photo you wish to view.
Tap the photo you want to open.
Turn your iPhone 90 degrees to the left or to the right so that you are holding the phone horizontally. The photo will automatically rotate.
Turn your iPhone back to its original position to rotate the picture back to the original format.