Press and hold the top button until the power-off slider appears. Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force-restart your device. To turn your device back on, press and hold the top button until you see the Apple logo.
If iPhone isn't responding, and you can't turn it off then on, try forcing it to restart. Press and quickly release the volume up button. Press and quickly release the volume down button. Press and hold the side button.
Reset iPhone in Recovery Mode
There is a final way you can try if force restarting is either not working. That is put your iPhone into recovery mode and reset it with iTunes. This is a final method you can try since iPhone data will be erased after reset.
iPhone with Face ID: Simultaneously press and hold the side button and either volume button until the sliders appear, then drag the Power Off slider. iPhone with the Home button: Press and hold the side button, then drag the slider. All models: Go to Settings > General > Shut Down, then drag the slider.
Your battery is low. Your iPhone is running out of storage space. Certain apps are incompatible with your software. Your operating system is outdated.
If your phone is frozen with the screen on, hold down the power button for about 30 seconds to restart.
Using recovery mode
This method works on Android devices only, for this, you need your Android phone to be turned off. Simply plug in your USB cable and keep holding down the volume down/volume up button to enter the recovery mode. Here when the menus appear, simply tap exit, and reboot the device.
How do you fix an Android phone that won't turn off? If your Android is frozen, try restarting it by holding the Power button down for about 30 seconds. Download the latest app and Android OS updates and clear some space on your device's hard drive if possible.
Another way to reset your iPhone is to do what Apple officially calls a “force restart.” Once again, no important data will be lost. A force restart is recommended when your iPhone is completely unresponsive.
It terminates all running apps without allowing them to “clean up” any process in progress, so it can cause data loss in apps that are running (just like it can on a computer). But it won't cause any damage to hardware or iOS. The better way to restart (unless the phone is frozen) is to shut down, then start.
When it comes to your iPhone and iPad, you should restart them once per week. As we said, this will help wipe the memory clean, and it might make your iPhone or iPad feel like it's working faster. You might not feel like it needs it, but the older your device gets, the more it's going to need a quick reboot.