How do I lock/unlock Fn button on apple laptop keyboard

I am using a Macbook Pro keyboard on my desktop (which is not an Apple) and after installing a hefty Windows update yesterday the function buttons no longer work as they did before. Before the update, pressing F1 would register an F1 button press, but this is no longer the case. In order to have an F1 button press registered now, I need to press Fn + F1 which is inconvenient. I would like to know if it is possible to revert to how things were before the update in this regard, without rolling back the update or performing a System Restore. I have searched for solutions using google but nothing has worked as yet. I have tried the following:

1. Entering BIOS to try to change the behaviour of the function keys (I saw nothing to allow me to do so)
2. Holding Fn + Esc and also Fn + a number of other buttons.
3. I looked at downloading something with which one can build one's own driver, but it says this in the notes:

, Windows will not directly allow the driver installation unless in TESTSIGNING mode. Please be aware that permanently running Windows in TESTSIGNING mode leaves your system open to potential security risks

so I don't wish to try this option. That said, here's a link for that option, in case it's of use or interest:

https://github.com/samartzidis/WinAppleKey

Any help appreciated.