Fix second monitor not detected
Press Windows+P and make sure Extend is selected, then open Settings, System, Display, Multiple displays and select Detect. If the screen stays dark, reseat or swap the cable, try another video port, press Windows+Ctrl+Shift+B to reset the graphics driver, and update or roll back the display driver.
Checked October 30, 2026 against the manufacturer's own pages.
The short version
What to install and where it comes from. Every link goes to the manufacturer or Microsoft, never to a copy.
Official files only, nothing bundled
Step by step
Pick Extend with Windows+P
Press the Windows logo key and P together. Choose Extend to spread the desktop over both screens. PC screen only turns the second display off, which looks exactly like a monitor Windows cannot see.
Select Detect in Display settings
Open Start, Settings, System, Display. Expand Multiple displays and select Detect. If the monitor appears, use Identify to see which number belongs to which screen, then drag them into place and select Apply.
Check the cable, port and input
Unplug docks, dongles and adapters and connect the monitor directly. Make sure the cable is firmly seated, try a different cable, and try another video port such as HDMI or DisplayPort. Set the monitor's input to the port you used.
Reset the graphics driver
If it worked before and suddenly stopped, press Windows+Ctrl+Shift+B. If nothing changes, restart the PC from Start, Power, Restart.
Update or roll back the display driver
Run Windows Update first. If the trouble began after a driver update, open Device Manager, expand Display adapters, right-click the adapter, choose Properties and on the Driver tab select Roll Back Driver.
Reinstall the display driver
In Device Manager, right-click the display adapter, choose Uninstall device, tick Attempt to remove the driver for this device and select Uninstall. Restart, then right-click the adapter, choose Update driver and Search automatically for drivers.
Rule out the monitor itself
Plug the monitor into a different computer or a game console. If it stays blank there too, the fault is the monitor, its power supply or the cable, not Windows. If it works, the problem sits with your PC’s port, settings or graphics driver, and the steps above apply.
Laptops with two graphics chips
Some PCs have more than one display adapter, for example a graphics chip inside the processor and a separate graphics card. Microsoft suggests switching the default adapter on such systems, often through the graphics software you open by right-clicking the desktop. The steps vary by device, so check your PC maker’s support page.
Where to get a newer graphics driver
On a laptop or prebuilt desktop, start with the driver your PC maker publishes, because it is tested on your hardware. On a desktop with an add-in card, use the card maker’s site: NVIDIA, AMD or Intel. Device Manager lists the maker and model of your adapter under Display adapters.
Questions
Can a splitter give me a second screen?
Not an extended one. Microsoft notes a splitter copies the same signal to every output, so both monitors show the same picture instead of separate desktops.
My laptop has only one video port
One port means one external monitor by default. A docking station from your laptop maker, or a USB-C adapter with an extra video output, can add another.
One monitor works but not the third
Your graphics card may not support that many displays. Find its maker under Display adapters in Device Manager and check how many monitors it can drive.
How do I add a wireless display?
Press Windows+K to open Cast and pick the device, or use Connect under Settings, System, Display, Multiple displays.