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, tap Apps (located in the lower-right).
These instructions apply to Standard mode only.
From the PERSONAL section, tap Backup and reset.
Tap Reset settings.
Tap Reset settings (located at the bottom)to confirm.