How can I modify the screen brightness in Ubuntu 14.04 LTS ? In the Systems Settings -> Brightness & Lock screen, all I see are options related to the screen saver, but nothing for changing the current screen brightness. Shouldn't there be a scroll bar for brightness level in this window ?
Finally found the issue... When this happened I had booted Ubuntu in recovery mode. Some options are not available in recovery mode, such as adjusting screen brightness and using multiple monitors.
When I booted back in normal mode, the screen brightness adjustment settings were available.