Open Control Center by swiping up from the bottom of the screen (or swiping down from the top right on iPhone X and newer). Tap the Lock Rotation / Lock Orientation button a second time, so that the ...
You can use an Accessibility feature called AssistiveTouch to rotate your iPhone or iPad screen without tilting it. Once you have enabled AssistiveTouch, tap the ...
Check if the Portrait Orientation Lock is on; it stops the iPhone screen from rotating. Open Control Center and tap the lock icon to turn off rotation lock if it's active. Some apps don't rotate; test ...