With laptop brightness not working, the slider in Settings may be missing, may move without changing anything, or the brightness keys may do nothing. The screen can also be stuck very dark or very bright, or the brightness may jump back after you change it.
The screen panel is rarely at fault here. Windows controls brightness through a display driver and a small monitor entry, and when either goes wrong the slider loses its effect. Use these steps in order, starting with the quick key and power checks. If the whole screen is dark or black, use laptop screen not working for the wider display checks.
Common causes
1Display driver outdated or wrongly installed
How to tellSlider moves but the screen stays the same, or the slider is missing
What fixes itUpdate the display adapter driver using Windows Update
2Generic PnP monitor disabled in Device Manager
How to tellBrightness slider disappeared, usually after an update
What fixes itEnable the Generic PnP Monitor entry under Monitors, then restart
3Brightness keys need the Fn key
How to tellBrightness keys on F-row do nothing when pressed alone
What fixes itHold Fn and press the brightness key, or toggle Fn Lock
4Auto brightness or battery saver changing the level
How to tellBrightness drops by itself, or goes dim on battery
What fixes itTurn off Change brightness automatically and check Battery saver settings
5Outside monitor connected or duplicate mode
How to tellSlider works only for one screen or does not appear when a monitor is plugged in
What fixes itUnplug the external screen and test again
6Backlight or inverter hardware fault
How to tellImage is visible with a torch but very dark, and does not change in any mode
What fixes itTechnician checks the backlight, panel cable or the screen
How to fix it, step by step
Try the brightness keys with Fn
Look for keys with a small sun drawing, often on the F-row. Press them alone, then hold Fn and press them. If neither works, look for an Fn Lock key or try Fn + Esc to swap the key mode.
Use the slider in Settings or the quick panel
Open Settings, then System, then Display, and drag the brightness slider. On Windows 11, press Windows key + A to open quick settings, which also has a brightness slider. If the slider is missing, the monitor entry or driver is the issue.
Restart the laptop with the charger unplugged
Restart once with the charger out and once with it in. Some laptops store a separate brightness level for plugged in and battery use, and a restart refreshes both. Check whether the problem appears only on battery or only on charge.
Enable the Generic PnP Monitor
Open the Start button menu, pick Device Manager and expand Monitors, and if you see a down arrow on Generic PnP Monitor, right-click it and choose Enable device. If it is enabled already, choose Disable and then Enable, which refreshes it. Restart afterwards.
Update the display adapter driver
Under Display adapters, right-click each graphics entry and let Windows look for a newer driver. Many laptops have two entries, a basic one and a stronger one, so update both. Never install drivers from sites you do not recognise.
Roll back or reinstall the driver
When the trouble began just after a driver update, open the adapter's Properties, go to Driver and choose Roll Back Driver. If that is greyed, pick Uninstall device and reboot, and Windows fits a basic driver that includes brightness control.
Check power plan and adaptive brightness
Open Power Options from the Start search, edit your plan and open its advanced settings, then look under Display for brightness entries and adaptive brightness. Set the levels as you wish and turn off adaptive brightness if it keeps changing. Also check the content adaptive option under Display settings if shown.
Reset the power plan and run Windows Update
In Power Options, choose Restore default settings for this plan. Then run Windows Update and restart. A pending update is sometimes the missing piece that brings the slider back.
Laptop brightness not working: Windows 11 against 10
On both versions the logic is the same. Windows asks the monitor for a brightness range, and the monitor entry in Device Manager answers. If the answer is missing, the slider is hidden or inactive. On Windows 11 the slider is in Settings, then System, then Display. On Windows 10 it sits in the same place, and also appears in the action centre. A common cause is an update that swapped a display driver for a basic one, which is why rolling back or reinstalling from Windows Update solves most cases.
You open Settings and the brightness slider is simply gone. In Device Manager the Generic PnP Monitor shows a down arrow. You choose Enable device, restart, and the slider returns.
Brightness keeps changing or resets by itself
Three features can adjust it silently: adaptive brightness using a light sensor, battery saver that dims the screen, and a battery plan that lowers brightness after a short time. Switch off adaptive brightness in Power Options and check Battery saver in Settings, then System, then Power. Windows also lowers brightness when the lid is open but the laptop is idle, which is controlled by the display dim setting in the power plan.
Brightness works but the screen is still too dark
If you can change the slider but the picture stays dim, try the screen with a torch to see whether a faint image remains at maximum. If yes, the backlight may be failing, or the cable at the hinge may be loose. That repair is for a technician, and its cost varies by the model, plus whether the backlight is a separate part. Also check colour filters such as night light and high contrast settings under Display and Accessibility, which can make the screen look dim. A black screen of any kind has its own guide at laptop display not working.
Keep the screen brightness moderate on battery to extend runtime. A permanently max setting also warms the laptop; see laptop fan not working if heat is a concern.
Other devices that look similar
Phones have their own brightness faults, such as auto brightness and a proximity sensor that dims the screen on a call, discussed on the proximity sensor not working page. For the general laptop checklist, use laptop not working.
Frequently asked questions
Why is my laptop brightness not working on Windows 11?
The display driver or the Generic PnP Monitor entry is the usual cause. Enable the monitor in Device Manager, update the graphics driver and restart.
Why did my brightness slider disappear?
The monitor entry in Device Manager is probably disabled or a driver update changed. Re-enable it, or uninstall the display adapter and let Windows reinstall it.
Why is the brightness button not working?
Many laptops need Fn pressed with the key, or have Fn Lock turned on. Try Fn plus the key, then Fn + Esc to swap modes.
How do I turn off auto brightness?
Open Settings, then System, then Display, and turn off the option that changes brightness automatically. Also check adaptive brightness in advanced power settings.
Does low brightness mean the screen is damaged?
Not necessarily. Software and power settings cause most cases. Only a dim image that no setting changes, even with a torch test, points to a backlight fault.