Restoring your device to default settings helps when the device crashes and resets itself or when apps freeze/hang or reset the device.
Performing these steps resets all system settings (e.g. ringtones, sound settings, display settings, etc.) back to their default values. Personal data, such as downloaded apps and media (pictures, videos, music), aren't affected.
From a Home screen, swipe up or down from the center of the display to access the apps screen.