From any screen, press and hold the power button to bring up the power context menu. Select “Reboot” to initiate. This option functions as more of a soft reset and most minor issues will be solved by restarting.
To do Factory reset:
Access Settings from the apps menu. Scroll down to “Backup & Reset” and tap the text to go into the category. Choose “Factory data reset” from Backup & Reset section. Please note this will remove all data from the phone and is not recommended as a remedy for minor issues.