Help my 'fn' problem at acer d255

Hello,
i have a problem with my netbook, my netbook is acer aspire one d255.
at the first time,if i type fn+f3, or fn+fkey that will be notification at the screen ,
for example, if i want to turn off the wifi i will type fn+f3, and there will be notif
wireless on/of ,bluetooth on/off .but now, if i type fn with f3-f12 thre's no response and notif at the screen, but the function still working . i just wanna make it back ..
please help me :"(