I am using Lenovo G505s with Windows 8.1.From past few days my brightness was unnable to change (*both Function keys on keyboard and brightness slider on right options).Then while i was unable to change my brightness was set to maximum I managed with this hoping it will solve if I get any updates. But today I suddenly my MAXIMUM brightness was set to LOW. I cannot change the brightness and it is fixed to low.I was unable to do anything.