Some FN keys do not respond

Hi everyone,

I recently use an iMac Late 2009. I accidentally installed Developer version of 10.7.2 Mac OS X Lion, considering it is the official one. After giving it a look on the net, I found a way to go back to 10.7.1. After that I installed the official one. No problem till here.

The keyboard issue began after that. F1,F2,F3,F4,F5,F6,F7,F8 and F9 do not respond. I checked it using virtual keyboard on MAC and I can't click on these buttons on the virtual keyboard as well.

Yesterday, I upgraded my iMAC to 10.7.3, but nothing changed.

So any suggestions for the issue?

 

Thanks for your help, I just tried that, but the problem still exists.

 

Thanks for your advice. Just realized that, this might be the issue. I can't pass the step "changing keyboard type". it says " your keyboard is not identified."