Hello, my name is Jan and I'm happy to help you today. I'm sorry you're having this problem. Ensure that the HDMI/Display cables are attached properly, then press the Windows key + P and select Extend. If that didn't work, here are a few things you can try.
- Power cycle/reset your computer.
Press the power button for 10 seconds to turn off
then unplug your AC adapter for 30 seconds
then plug in your adapter.
then start your device.
- Press Windows Key + X
select Device Manager.
Expand the Display Adapter
select the graphics driver
Try to disable and re-enable the driver
then connect and extend to your second monitor again.
- Uninstall the graphics card driver and let Windows download the driver using Windows Update.
Press Windows Key + X
select Device Manager.
Expand the graphics card
then right click on your graphics card
then uninstall.
Check the box "delete the driver software for this device"
Then click on uninstall.
restart your computer.
Then open Windows Update and click Check for Updates.
It should download the latest graphics driver and install it.
- Manually reinstall the graphics driver. Download the latest driver from the manufacturer's site and install it. Also, try the old driver if the latest driver does not work.
If you have Nvidia or AMD graphics, select the custom install and
Perform a clean install option.