Sony Xperia V LT25i can now be updated to Android 4.2.1 CM10.1 Jelly Bean custom ROM. There is no word on when will Sony release the official software update for Android 4.2.1 for the Xperia V, but a big thanks to the FreeXperia and CyanogenMod teams to bring this latest Android version to this phone.
Make sure battery is full.
Go to menu: Setting > Backup and reset > Factory Data Reset > Reset Device
Choose Erase Everything
It will start process to restore Factory mode, wait for several minutes.
Hard Reset by Code
Make sure the battery fully charged
Backup all your important data
Power on
On dialer enter this code: *#*#7378423#*#*
On the screen Select -> Customization Settings
Then select -> Reset customization and confirm.
wait for several minutes.
Hard reset by button
Switch off your cell phone.
Next hold and press Power button + Volume Up for about few seconds.