First method:
- Check that if your phone is on.
- Browse to Settings -> Backup & reset -> Factory Data Reset -> Reset Phone.
- Select option option "Erase everything", and confirm that.
- Finito!
Second method:
- First download flashtool from Sony website: http://developer.sonymobile.com/services/flash-tool/
- Make sure, that you have installed drivers for your USB data cable.
- Switch off your cell phone.
- Hold and press Volume Down, and connect to USB cable.
- Please follow the instructions in your screen, and accept appropriate options.
- Good job!
Third method:
- Power off your device.
- Next hold and press Power button + Volume Up for about few seconds, or until you see menu of your screen.
- Afterwards follow the instructions on your screen.
Fourth method:
- Back up your important files, and download PC Companion from here: http://www.sonymobile.com/gb/tools/pc-companion/
- After installation you will see window with 4 options.
- Now hover your mouse over the option "Support Zone Now!" and click "Start".
- Next plese wait, until your program Install a suitable additive.
- Afterwards from the window with 3 options choose "Phone / Tablet Software Update", and click "Start".
- Then click to "repair my phone / tablet".
- Accept all informations.
- Now your program will run "preparing computer for software update".
- Select your model.
- After that you will see window with informations.
- Follow the instructions, and connect your device into your Personal Computer.
- Success!
Fifth method:
- Power off your cell phone.
- Then hold and press 3 buttons: Power button + Home button + Menu button.
- Now if you feel, that your phone vibrates, then release only Power button.
- After that follow the instructions.
- Done!
Sixth method:
- Turn off your phone.
- Press and hold three buttons: Power + Back + Menu.
- Realese Power key when your device vibrates and still hold the other two keys.
- You can realase held keys when you see new menu on your screen.
- Enter emergency dialer and tap this code: *#*#7378423#*#*
- Then tap customized settings and select reset customization.
- Now your phone will reset and restarts.