How do you make the shortcuts on an apple keyboard work with windows?

i Recently bought an apple keyboard for my mac because the one that originally came with it stopped working. However i got it working again so i decided to use the spare keyboard (the brand new one) with my PC. I found that the function key ("fn") in conjunction with the f1-12 keys don't work, i.e fn+f10 should mute volume, but that doesn't happen. How can i make these shortcuts work?