1 Answer

Video tutorial > http://www.butterscotch.com/tutorial/How-To-Factory-Reset-Your-Android 

 A factory reset will revert your Android phone back to the way it was when it was first shipped. Everything except OS updates will be wiped out.

- This means that any personal data like passwords, pictures, videos and so on will be deleted. This makes it a great option for just before you sell or give away your phone.

- During troubleshooting, a factory reset is also seen as a last ditch way of clearing up any problems that the phone might be having.

- To get to the factory reset option you'll want to go to Settings, then tap Privacy.

- Before performing a factory reset, it is a good idea to ensure that both Back up my data and Automatic restore are checked.

- When you tap Factory data reset, you'll be taken to another screen that will advise you of what's going to happen. You'll also be given the option to erase internal USB storage or SD storage.

- Keep in mind that the factory reset is irreversible. When you are certain you know what you're doing, tap Reset phone to start the process. This can take several minutes and require the phone to power on and off several times. 

http://www.butterscotch.com/tutorial/How-To-Factory-Reset-Your-Android