Funtion buttons not working after Win 10 upgrade

I upgraded to Win 10 (from Win 7)and now many of the Function buttons not working ie F2 and F4 for booting into BIOS and Recovery. Can't manipulate sound, screen brightness or eject a CD using the Eject button?? Have upgraded as many of the drivers that I can find. Anyone have a solution. It seems to be a common problem on the net? Samsung I 7 series laptop.