Step 1: Press and hold the power button on the right side of your iPhone.
Step 2: At the same time, press and hold down the Volume Down button on the left side while keeping the power button pressed.
Step 3: Keep holding both the buttons until the screen turns black, don’t let go, wait until you see the apple logo then let go.
Step 4: Wait for a couple of seconds until your iPhone boots up completely and displays the Lock screen.