Hi,
Start the troubleshooting by connecting and external monitor and see if you'll get any display from it and if you do press the Windows key + P at the same time and select Disconnect Projector or Display only then press Enter. If these will not work here are more troubleshooting steps you can try.
- Do a hard reset first, for desktop PC just unplug the power cable then press and hold the power button for 20 seconds. For laptop remove the battery and charger then do the same.
- If it will not load the desktop screen, press CTRL + ATL + DEL at the same time and select Task Manager. Click File then New Task and type in explorer.exe and click OK.
- If all these will not work try loading it into Safe Mode. While the PC is booting up repeatedly press on F8 until it shows Advanced Boot Options. Select Safe Mode and press Enter, see if it will load the desktop screen.
- If all these will not work you may need to reload the original OS of your PC since it may be a bad install of Windows 10.