Perform a soft, factory, and alternate master reset of the device.
INSTRUCTIONS & INFO
There are multiple ways to reset your device if you are experiencing issues. The first step is to power cycle your device by pressing and holding the Power/Lock button > Power off. Then once the device is off, press and hold the Power/Lockbutton to turn the device back on. Note: If device is unable to power off, press and hold the power button for 10 seconds.
If a power cycle does not resolve your issue, perform a device restart. To restart the device tap and hold the Power button then tap Restart. Note: If you are unable to access the screen to Restart the device or if it becomes unresponsive, press and hold the Volume down and  Power/Lock button  simultaneously for 10 seconds, until the device restarts.Â
To perform a factory data reset Swipe down from the top of the screen with two fingers and tap the Settings icon > Backup & Reset > Factory data reset > RESET PHONE > ERASE EVERYTHING.  Note: A factory data reset will revert the device back to factory settings. It will permanently erase all personal data, preferences, settings, and content such as pictures, ringtones and apps that are saved to the device.  It is recommended that you save/backup important data before proceeding.