Try this... it will restore your "knock on" but will not fix "knock code". If you really really want "knock code" to work I have the files to flash over your aboot and boot partitions to restore that, but it's a little more risky.
This will take you to the "Hidden menu"
Select "Update Touch Firmware"
Your phone may seem like it froze for a short period (30 sec to a minute if I remember)... it will react again.
Last edited by daryelv; 29th June 2014 at 01:13 AM.