2. When the start-up screen appears, release the Power key while continuing to press the Volume Up/Down keys.
3. Continue to press the Volume Up/Down keys for at least 8 seconds, until the Android System Recovery screen appears.
4. Release the Volume Up/Down and Power keys.
5. Use the Volume Up/Down keys to scroll to wipe data/factory reset, then press the Power key to select the option.
Note , anythime you want to do a hard reset on your Samsung Galaxy S III, do remember to back up some useful data such as phone book and kinds of files. Don’t worry about the downloaded apps, you can redownload it and don’t have to pay for it again.