My laptop is a lenovo z50-75.
When I try to up or down the brightness the screen stays with the same brightness.
I try to upgrade the drivers of my graphics but it says they're with the most recent driver.
I go to control panel and there, there is a "brigtness bar" and there I can up or down the brightness but in real world doesn´'t up or down the brightness.(IT happens the same with the keys of brightness of my keybord)
I already solucionated the problem, it was a problem of drivers but thanks you for answer me
Great you found a solution!
Vendor specific driver?, normally Windows gets those drivers from Windows update on first install. If it where a quick launch button driver problem you still vould have been able to adjust from control panel - power options.