If you have an iPhone X or newer, press and hold either volume button and the Side button until the “slide to power off” slider appears on the display. Your iPhone will turn back on shortly after. Wait a few seconds, then press and hold the power button again until you see the Apple logo flash onto the screen. Swipe the slider from left to right to turn off your iPhone. To restart your iPhone 8 or older model, press and hold the power button until the words “slide to power off” appear on the display. This can sometimes fix minor software glitches causing problem on your iPhone. If you tried opening Control Center the normal way, but it still isn’t working on your iPhone, it’s time to begin troubleshooting for a software problem. Make sure you’re swiping down over the battery icon! Restart Your iPhone

Once again, if you’re having trouble opening Control Center, you may not be swiping from high enough up or far enough right. Swipe down from the upper right-hand corner of the display to open Control Center. If you have an iPhone with Face ID, opening Control Center is a little different.