IT' actually really simple if You have vista or windows 7. Just in start search bar write "mobility" and look in search results for " Windows mobility center". A window will open. find Fuction key in that and select "Function Key" instead of "multimedia"(or any thing else) and that's it.
THIS LOCKED MY F1 F2 F3 F4 F5 AND SO ON KEYS. I GOT THIS FROM ANOTHER WEBSITE FROM SOMEONE ELSE THIS SHOULD HELP YOU NIGTHER SMITTER