Press and hold the Volume Up and Home keys with the device turned off to access the factory reset options. Use this method to perform a factory reset on a Samsung Galaxy S3 no matter which carrier you use.Continue Reading
Press and hold the Power button to turn off the Galaxy S3. Alternatively, remove the battery to turn off the handset completely, and reinsert the battery into its slot.
With the device turned off, press and hold the Volume Up and Home keys. Next, press and hold the Power key until the Samsung logo appears on the screen.
Wait for the Samsung logo to disappear and reveal the system recovery options. Press the Volume Down key to scroll to the Wipe Data/Factory Reset option.
Highlight the Wipe Data/Factory Reset option, and press the Power key. Next, press the Volume Down key to scroll to Yes -- Delete All User Data. Highlight this option, and press the Power key.
Once the factory reset completes, press the Power key to select Reboot System Now. Afterward, follow the on-screen prompts to set up your Samsung Galaxy S3.