When you buy a new cell phone, it comes with numerous default settings in place. These settings tell the phone which ringtone and time zone to use, and keep the phone unlocked so that you do not need a password to get into it. You are given options to change all of these settings during the phone’s initial setup. If you've customized your phone and want to restore it to its factory settings—if you're giving it to someone else, for instance—you can perform a basic reset.
Look for your phone's reset button. The reset button causes a hard reset of the phone, which erases all data added to the phone since it left the factory. To reset your phone, insert the tip of a straightened paper clip or a pin into the hole, press the button for 5 to 10 seconds, and release. If your phone doesn't have a reset button, try holding down the power button for at least 20 seconds and then letting go. This resets some units.
Some phones, such as iPhones, provide a built-in Reset feature for resetting all of the settings that have been added to the phone since it left the factory. To use this feature, go to the Main Menu, look through the categories until you find "Reset," and then choose “Reset all settings.” All customizations, including passwords, are lost, but the phone doesn’t delete media and other files.
To truly return your phone to factory condition, you should eliminate not only the phone’s settings but any files or programs as well. Open the Main Menu, choose the "Reset" option, and choose “Erase all content and settings” to restore the phone to factory settings and clear all files from the device.