How to brighten monitor
i have a few thing to help you with this problem, but first if the monitor old, used a lot or left on all the time than it is time for new on.
first right click on screen using the mouse than go down to screen resolution than find the detect button after thats done go to Identify
select that one, after you done all that than go to advanced settings and open the folder, than check the adapter, monitor, troubleshoot, color management, than select color management check all settings.
2 way is to go to control panel open color management folder, for your general information for you monitor and other options you mite want to review understanding color management settings find advanced tab find calibrate display, it will run a lot of tests and have you answer some question about visual site and what you like in the settings of the monitor.
you mite look in to video card manufacture and see if they have any tools for the drivers game apps or programs that runs other than video card drivers, like i have nvidia video card and i went to there website and downloaded so software, nvidia control panel for gamers, 3d adjusting color settings and video image settings, change the aspect ratio, resulation, refresh rate, lots of tools for games and gamers and i do not play a lot of games but i like to have a lot of option that i would not have had before.
thank you rod
PS make sure all drivers are up to date you will find it in control panel and than open device manager and find video drives, monitors, display adapter.