. Turn off the phone completely.
2. Press and hold both Volume UP (and HOME) + power on the phone.
3. When Android Recovery menu screen appears release all keys.
4. Navigate and highlight wipe data / factory reset using the Volume down key and press power.
5. Navigate and highlight again to Yes - delete all data and press power.
6. All data will be lost! Before doing a hard reset backup all important data.
After hard reset is done select Reboot system now. Press power to reboot the phone.
More..... http://www.hard-reset.com/samsung-galaxy-j7-hard-reset.html
