How to reset iPhone (hard reset & reboot)
Your iPhone will run quite smoothly for the most part, but some situations call for a manual reboot or so-called hard reset. For example, an app might become unresponsive or your iPhone locks up completely and/or acts in a strange way, this is when a full reboot is recommended. This guide shows you how a proper reboot procedure can be initiated without any further tools or software.
How to reboot iPhone manually
If you need to restart your iPhone’s operating system, there is really only one way:
Holding both the Sleep/Wake and Home button for roughly ten seconds will trigger a reboot. Depending upon your iPhone model, you might find the Sleep button on the top or the right hand side of your device. If you own the iPhone 6, for instance, your Sleep/Wake button is on the right side of the device.
Be sure to press and hold both of them for the desired result, otherwise you might simply end up with Siri or the shutdown menu. Should you see the shutdown pop up while trying to reboot, ignore it and continue holding the keys. In any case, hold and wait until you see the Apple logo – then let go immediately. Your iPhone will take a minute or two for the subsequent startup procedure.
Is this procedure dangerous?
Rebooting your iPhone with the above method does not result in resetting or loss of e.g. your settings or personal data. It is simply a way to restart all running processes and the underlying system while provoding an opportunity for smooth operation after a fresh bootup.
Many temporary glitches and issues with misbehaving apps tend to fix themselves, so to speak, after conducting a hard reset with your iPhone.