SONY XPERIA Tablet S - Factory / Hard reset
There are two ways to perform Factory Reset:
Metod 1:
Open "Settings", tap "Backup & reset", "Factory data reset"
The tablet will restart automatically.
Metod 2:
Power of the tablet. Pres and hold the Power On key and the Volume Up key at the same time.
When you see the Sony logo release the Power On button but continue to press the Volume Up button.
Now you are in the Android recovery menu.
Use Volume keys to scroll and the Power On key to select.
From the options select:
"Reset to Factory Settings" and "Yes - erase all user data".
The tablet will restart alone.
Video tutorial:
https://www.youtube.com/watch?v=9NM2znQk558