(Tutorial)boot-loader unlock any Xperia topic

First get unlock key from here
http://unlockbootloader.sonymobile.com

For your phone IMEI no. Dial *#06#
1)Check that device is boot loader unlock-able.
2)Open dialler dial *#*#7378423#*#*
3)Tap service info
4)Tap Configuration
5)Check for Boot loader unlock allowed
6)If yes you can proceed (If no don't you might brick your device)
7)Download flashtool from here http://www.flashtool.net
8)Install flashtool
9)Open C:/flashtool/drivers.exe
10)Instal driver for your phone,flash mode and fast boot mode.
11)On your device enable Usb Debugging from setting, Developer options
12)Open flash tool
13)Tap on BLU
14)Power off your device
15)Connect Usb Cable while pressing Volume down.(Flash mode)
16)Connect Usb Cable while pressing Volume Up.(Fastboot mode)
17)Enter Key which you got from Sony
18)Your boot loader should now be unlocked.

If help press the Thanks Button.