My iPhone is frozen and I don’t know how to restart it

Hold down the “Home” & “Sleep/Wake” button (located top right corner of the phone) simultaneously.
Keep the buttons held down until the screen goes Black and the Apple logo appears.
iPhone is rebooting at this point. Restarting or shutting down your iPhone will not delete any of your data. It is a safe procedure and is how you recover from a crash or in your incident it locked up