First method:
- Press Power button until your phone is on.
- Next goto Settings -> Backup & reset -> Factory Data Reset -> Reset Phone -> Erase everything.
- Confirm that operation.
- Done!
Second method:
- Download program named flashtool from Sony website: http://developer.sonymobile.com/services/flash-tool/
- Then check, that you have installed drivers for your USB data cable.
- Now turn off your handset.
- Afterwards press and hold Volume Down, and connect to USB cable.
- Accept all informations.
- The end.
Third method:
- Switch off your phone.
- Then hold and press together Power button + Volume Up for about few seconds, or until you see menu of your screen.
- Follow the instructions on your screen, and confirm operations.
Fourth method:
- You should first download and install program PC Companion.
* In example from here: http://www.sonymobile.com/gb/tools/pc-companion/ - If all went well, you will see window with 4 options.
- Next click "Start" under the name "Support Zone New!".
- Wait until the process of the installation is completed.
- Now you should see window with in example option "Phone / Tablet Software Update".
- Accept this option -> click "start".
- Then click "repair my phone / tablet".
- Please follow all instructions, and confirm that.
- Read "Inportant information", and confirm.
- Afterwards PC Companion is "preparing computer for software update".
- Next select your phone / tablet model.
- Follow steps, which you see in new window.
- That's all.
