Why are apple f keys not working?

You can get your f keys work again through the following ways,

1. Open System Preferences / Keyboard / Keyboard shortcut and remove the check from in front of the items that says ‘Use all F1, F2, etc. as standard function keys.’
2. In case of new Apple wired Aluminum board with numeric keypad keyboard, please note that the requirement of OS has changed from being 10.4 to 10.6.8.
3. There have come new keyboards with function modifier key (Fn). It means when you want to use f keys, you will have to press and hold the fn key while pressing any of the f keys, f1, f2 or any. But this does not apply to f5 and f6 keys.
4. You could also try and use a different keyboard with your computer or try using your keyboard with a different Mac.
5. Try log in from a different user account.

Go online and look for a software update online and it will help you with the f key issue.