Restarting (Resetting) your iPhone.
Many times, restarting your iPhone will correct lots of problems you may be having.
Press and hold one of the volume buttons and the side button until the power-off slider appears.
Drag the slider, then wait 30 seconds for your device to turn off.
If your device freezes or doesn’t work, force restart your device.
To turn your device back on, press and hold the side button (on the right side of your iPhone) until you see the Apple logo.
How to restart an Android Phone
Restart your Android phone by holding the Power button. Then select Restart or Power off and Restart from the Power Options menu.
Note: On new Samsung devices you must hold the Power / Side button and Volume Down. This makes the Power Options menu appear.
How to restart a Mac
Go to the Apple menu in the upper left-hand corner
Select shutdown or restart if you just want to restart it.
If you cannot access the Apple menu, you can force quit your Mac by pressing and holding the power button.
Press the power button again to restart.
How to restart a PC
Go to the Windows menu.
Click on the Power button and select Shut down or Restart.
You can also press and hold the Power button on your computer until it shuts down.