Android phones can be easily rebooted, or reset, without losing any information. A reboot is comparable to restarting a computer and can often be a useful first step in device troubleshooting. A reboot closes any running applications, even those in the background. If your device is running slower than usual, has frozen or has displayed an error message, try a reboot first. Other options for troubleshooting include a hard or master reset, which erases all personal data and returns your Android to factory default settings.
Unlock your device screen by touching the "Power" button once.
Press and hold the "Power" button. When the power options display on your screen, touch "Power Off." Your phone will shut down.
Press the "Power" button again to restart your phone.
Touch the "Applications" launcher on your home screen, then touch "Settings." A list of options displays.
Touch "Privacy." Touch "Factory Data Reset." Review the warning message displayed on your screen. All data stored on your phone will be erased.
Touch "Reset Phone." Another disclaimer appears, warning you that you are about to remove all personal information from the device. Touch "Erase Everything." Your phone will begin the reset process -- it can take up to 10 minutes to erase all data.
If your touch screen is frozen, you can also perform a soft reset by removing and re-inserting your battery.