how to disable or reverse FN key: I want to replace: FN+F1 , FN+F2, FN+F3, ... FN+F12 with simply F1, F2, F3, ... F12

You already have an answer, but I found easiest way to resolve the problem.

Just try press Fn + Esc once and its should help :)

I found this link and it was really helpful for me:

http://support.lenovo.com/pt_BR/downloads/detail.page?&LegacyDocID=MIGR-75582

I only followed the steps: i downloaded the zip file and extracted it. I installed it by clicking a double click on setup.exe

Now I can search from start - "Lenovo Slim USB Keyboard"

and just tick :

"Use F1-F12 as standard function keys"

:))

Thanks again for you @and31415 cz you let me found the key by searching for My keyboard model and I hope I will help the others with my answer