In order to hard reset a Samsung Galaxy S 4G T959, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Samsung Galaxy S 4G T959 device will be brought back to the default configuration of a brand new device.
1. Switch off the phone by press-holding the Power button.
2. Press and hold the Volume Up + Power + Home buttons until the Samsung logo pops onscreen.
3. Using Volume buttons to navigate to it and Power button to select it, choose Wipe data/Factory reset option.
4. Next, select Yes and Reboot system now.
5. Yay, the hard reset process is complete.