(Mac ibookG4)--Someone please help!!!

I opened my itunes as usual and wanted to adjust my volume,but it didsn't work. I tried adjusting the volume in the Control panel as well as made sure the (F1,F2 box is not checked), I know its usually not. And its still not working. While I am using Firefox, the usual volume key reloads the Firefox page instead of adjusting the volume. The contrast button is not working at all. I have no idea what to do, both volume and contrast only works if I manually changed them through the control panel

What I have done so far to recover:
I did shutting off, taking out battery, and holding the power button (Didn't work)
I also did the Control+Option+P+R and that didn't work either.
I also tired the RRAM and no hope!!!!

I had my ibookG4 for almost 5 years and never had a problem till now.Pleas help!!!
Thanks in advance!