I want to change the function of my F1-F12 keys?

Alright so my laptop is a newer model on a newer OS (8.1). I have come to the realization that my F1-F12 keys work backwards. When I press the F1 key it mutes my computer as opposed to doing it when I press the FN key. For a while I didn t mind, however, when I got into computer gaming it really started ticking me off. I have to hold the FN button whenever I want to use an ingame bind. This INFURIATES me, I can t even tell you how many guides I have looked on for an answer and no solution has worked. My computer wont allow me to access the Bootup OS setup screen (there is no option to) and I can t use a "One Key Recovery" button because I don t have one. I am at wit s end, I am just a few incorrect guides away from taping the d*mn FN button down.
I am running a Lenovo laptop on an Intel Core i5 (64-bit) with a Windows 8.1 OS

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