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.
Navigate: Settings > System > Reset options.
Tap Reset settings.
Review the info then tap RESET SETTINGS.
If presented, enter the current PIN, password or pattern.
To confirm, review the info then tap RESET SETTINGS.