Sometimes locking code is forgoten or not known, and there is need to factory reset the phone. All data will be lost, but in this case this is only way to access and again use Android phone.
- Switch off phone.
- Press and hold Volume Up key along with Power button and Home key. You will see the Samsung logo onscreen.
- Wait for text menu.
- Using Volume Up and Volume Down, go to wipe data/factory reset.
- Choose it using power button.
- Now choose Yes using Volume Up or Volume Down button.
- Choose it using Power button
- Wait for info that Wiping process on your phone is done.
- Switch off phone. This is end of process.