1.First get switch off your device by holding the Power key for a short while.
2.Puch and hold together: Volume Up + Home + Power button for a couple of seconds.
3.Get release held keys when the Samsung Logo appears on the phone’s screen.
4.After that tap to “wipe data / factory reset” using Volume buttons to navigate and Power button to confirm
5.After that choose “Yes — delete all user data” to confirm the whole operation.
6.After the Recovery Mode menu appears again select option “reboot system now“.
7.The hard reset has been performed .