Your iPad has an accelerometer which detects the angle at which you are holding the device. If you hold it vertically, the display will be portrait; if you hold it horizontally, the display will shift to landscape. However, you can lock the rotation to fix it in a certain position if you don’t want it to switch. This is handy if you’re reading in bed or using an app that requires you to move the iPad. If your iPad display has stopped switching, it’s most likely that you or another have locked it. Unlocking screen rotation is relatively straightforward.
Using the multitasking bar
Press the home button twice. This brings up your multitasking bar. The multitasking bar displays all of the apps that you’re currently using, even if they’re only running in the background.
Swipe right to left along the multitasking bar until you get to the leftmost app. The leftmost app is always the screen lock. You’ll notice that the screen lock icon has a small padlock overlayed on it to indicate that screen rotation is locked.
Tap on the rotation lock icon to unlock it. This disables the screen lock function and once again engages the accelerometer.
Turn the iPad to your preferred position. You’ll notice that the screen display switches accordingly.
Using the side switch
Tap Settings, then tap General. This opens a menu.
Scroll down to “Use Side Switch to:”. The side switch button’s default function is to mute the iPad, but you can set it to control screen lock. Tap on the checkbox next to “Lock Rotation” to enable this feature.
Slide the side switch down. This will unlock the screen lock. You can use the same button to lock the screen rotation again, or you can use the multitasking bar.
Turn the iPad to your preferred position and the screen will rotate accordingly.