When Apple's mobile phone is laid horizontally, the message theme is displayed on the left and the message content is displayed on the right.

Because the phone didn't unlock the vertical screen lock.

Solution: 1 Double-click the Home button. 2. Slide the page at the bottom of the phone to the far right. You will see an unclosed circle with an arrow. 4. Click on the circle and a small lock will appear inside. 5. At this time, there will be no horizontal screen on the mobile phone.