I have been using Ubuntu 13.10 for months now without too many hassles. But a couple of days back, my system offered to install this major update and of the many things that have gone wrong, the most prominent one is I am unable to change the brightness of my laptop (Dell Inspiron 15R) using my brightness hotkeys and as far as my knowledge goes, you can't do this graphically using Ubuntu's settings (please correct me if I am mistaken).
How can I rectify this? Please help my poor eyes!