If you need to restart your iPhone/iPad, just follow these steps:

• Press and hold the Power button for 3 seconds. 
• You will see an option at the top of the device that says Swipe to Power Off. 
• Please swipe in order to reboot device. 
• Wait a few seconds, then turn the device back on by pressing the Power button. You’ll see the apple icon, followed by the homescreen. Enter your passcode/use touch ID to unlock your device and continue.

That's it!