Hard Reset SAMSUNG P3110 Galaxy Tab 2 7.0

First method:

1. Turn on the tablet.
   
2. Now goto Menu -> Settings -> Backup & reset -> Reset device -> Erase everything.
3. Next you will see that you tablet will reset and restarts.
4. Done!

Second method:

1. Switch off your device.
   
2. Then press and hold this buttons:  Volume Up + Power button.
   
3. Now you will see Recovery mode menu.
4. Next choose option "wipe data / factory reset" using Volume buttons to scroll and Power button to accept your choice.
   
5. After that select option "Yes -- delete all user data".
   
6. In the end press Power button to confirm option "reboot system now".
   
7. Success!

WARNING !
Hard Reset will erase all of your data
All described operations you are doing at your own risk.