Restarting your iPhone is as simple as powering it off and turning it back on again. Here's how to restart your device for current and older models, and how to force restart if it's not responding.
The iPhone X eliminated the Home button, meaning the side button on the right replaced some of the functions of the Home button, such as waking or putting your iPhone to sleep. So just holding down just the side button doesn't do anything with newer versions.
To turn off your iPhone X or later, hold the side button and either one of the volume buttons on the left until the power-off slider appears on the screen. Swipe the slider and wait until your iPhone powers off.
To turn your device back on, press and hold down the side button until the Apple logo appears.
For older iPhones that have the Home button, the side button's primary function was for powering off your device. Press and hold the side button until the power-off slider appears and swipe the slider to turn off the device.
To turn your iPhone back on, hold the side button until the Apple logo appears.
The iPhone 5 and 1st gen iPhone SE has a button on the top instead of the side. Press and hold the top button until the power-off slider appears. Slide to power off.
To turn the device back on, press and hold the top button until the Apple logo appears.
If you iPhone is unresponsive and doesn't power off using the above steps, you can perform a force restart. To do this, press and release the volume up button, then press and release the volume down button. Next, press and hold the side button. Release the side button when the Apple logo appears.
