This is a menu used to test various functions on Sony Ericsson phones, which can help determine what is wrong, if there is a problem with your phone.
Go to Home screen. This is what displays your wallpaper, your operator logo, date and time etc.
Using the joystick / directional button, press ‘right’. (If you have a shortcut given to this key, do not worry about opening apps, this will not affect this work.)
Press the * key.
Press ‘left’, then ‘left’ again.
Press the * key
Press the ‘left’ key once more.
Press the * key one last time.
This should open the menu. The full code is: right, *, left, left, *, left, *.
The menu should read