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) are not affected.
From a Home screen, navigate: Apps icon > Settings.
From the Personal section, tap Backup & reset.
Tap Settings reset.
From the Reset Settings screen, tap RESET SETTING (located at the bottom).