Try this order, starting with the quickest checks:
- Press Windows logo key + P and make sure Extend is selected.
- Disconnect all accessories from the laptop, including docks, dongles, and adapters, because they can cause conflicts.
- Check that the monitor cable is firmly connected on both ends.
- Try a different cable. If the new cable works, the original cable was faulty.
- Test the monitor with another system to confirm whether the issue is with the monitor or the laptop.
- If the laptop has more than one video output port, connect the monitor to a different port.
If the setup worked before and then suddenly stopped:
- Press Windows logo key + Ctrl + Shift + B to reset the graphics driver.
- Restart the laptop: Start > Power > Restart.
- If restart does not help, use Start > Power > Shut down, then turn it back on.
If the problem started after an update, try the display driver steps:
- In the taskbar search box, type Device Manager.
- Open Device Manager and expand Display adapters.
- Right-click the display adapter, select Properties, open the Driver tab, and select Roll Back Driver if available.
- If Roll Back Driver is not available, reinstall the display driver:
- In Device Manager > Display adapters, right-click the adapter and select Uninstall device.
- Select Attempt to remove the driver for this device, then select Uninstall.
- Restart if prompted.
- Open Device Manager again, right-click the display adapter, select Update driver, then select Search automatically for updated driver software.
If the monitor is connected through USB-C, also check these points:
- Make sure the PC, external display, and cable all support the required display alternate mode such as DisplayPort, MHL, or HDMI.
- Connect the display or dongle directly to the laptop instead of through an external hub or dock.
- Make sure it is plugged into the correct USB-C port that supports the needed alternate mode.
If none of these steps works, file the issue in Feedback Hub and include the steps that reproduce the problem.
References: