My iPad’s screen does not rotate

Hi Yan, let's start with simple. Have you tried the following steps?

• Make sure that Portrait Orientation Lock is turned off. To check, open Control Center. If you see , tap it to turn Portrait Orientation Lock off.
• Restart your iPhone, iPad, or iPod touch.

Try a different app, like Safari or Notes. Some apps or screens only support portrait or landscape mode.

Swipe-down from the top right to reveal the Control Centre. The Screen Rotation lock button is this icon:

If you can’t find this icon, then you have an iPad with a side-switch on the edge of your iPad near the volume buttons. Slide this switch to the opposite of wherever it is now.

For info, the function of the side-switch is configurable - and is either set to control the Mute or Lock Rotation function:

Settings > General > Use Side Switch To:

Lock Rotation

Mute

If Mute is selected, the Lock Rotation icon/button appears in the Control Centre; by contrast, if Lock Rotation is selected, the Lock Rotation button is substituted by a Mute button in the Control Centre.

I hope this information resolves your problem.

Try here