Cool [Q] Andorid Downgrade from 4.1.2 to 4.0.4 on lg optimus l9 p765 without rooting

hi
Iam an User of lg optimus l9 p765. i have updated the firmware to 4.1.2 and iam unhappy with the update . i want to roll back to 4.0.4 without rooting my phone. can anyone help me with the procedure how to do it.

thanks in advance

MOhd Anwar