Volume buttons don't function

Hi,

I have a Sony PCG-GRT916Z notebook and since about a month ago the 2 volume buttons (located under the left and right click buttons) stopped working. I've tried everything within my very narrow level of experience and I don't know what to do anymore. I don't know if this happened because of my doing but I don't remember messing about with anything.

Also when I press the power off button that menu, with the "stand-by", "power off" and "restart" option, appears in the middle of the screen like it would when you'd click power off in the start menu. The power off button used to do nothing unless you held it for longer than 4 seconds and it would power the notebook off. Next to the power off button are the brightness control button and another with a magnifying glass on it to enlarge things. These buttons also don't do anything anymore. None of the buttons appear to be broken and haven't had any damage inflicted upon, they worked fine a month ago.

Any bit of help would be very much appreciated.

Thanks,
Sandro