keyboard key configuration

hi guys! i used to have window Vista on my laptop before and now i switched on to Windows7 and i dont know what happened since i installed windows 7 on my laptop my FN key isnt working properly i mean in general it is not allowing me to change the screen brightness and contrast for some reason i dont understand can u help on this one please

thanks everyone for ur help @ dwarf ur link was very helpful. at least i managed to find out the problem,but i am not able to fix it since its asking me to download the driver again which is to access VAIO Event Service since its completely deleted from the system and for that i have to reinstall the VAIO Event service to fix this problem but i think reinstalling this program will remove all the files i have on C: Drive which i cant do since i dont want to loose what i have on my pc. if there is anyway i can do this without loosing the files on my drive let me know please. or if u can direct me to the right site which will solve this problem by posting the link. thanks for ur help every one.