First method:
- Switch off your cell phone.
- Then navigate to Settings -> Backup & reset -> Factory Data Reset -> Reset Phone -> Erase everything.
- Now accept all informations.
- That's all.
Second method:
- Download and install program named flashtool from Sony website: http://developer.sonymobile.com/services/flash-tool/
- Make sure, that you have installed drivers for your USB data cable.
- Power off your device.
- Press and hold Volume Down, and connect to USB cable.
- Now accept all info.
- Finito!
Third method:
- First you should download PC Companion, in example from here: http://www.sonymobile.com/gb/tools/pc-companion/
- Install it and run.
- Next you will see window with 4 options.
- Choose option "Support Zone New!", and click "Start".
- Wait for the program to install the appropriate add-on.
- After that you will see next window with 3 options.
- Goto option "Phone / Tablet Software Update", and click "Start".
- Select "repair my phone / tablet".
- Now follow the instructions and accept all informations.
- Please be patient and wait until preparing computer for software update is complete.
- Afterwards choose your phone / tablet model.
- If you see this window, then connect your device into your PC.
- Done!
