If your screen should go blank in Windows the display driver may have crashed.
To restart the display driver in Windows press Windows + Ctrl + Shift + B and Windows will attempt to restart the display driver and that may bring back your display again. If this does not help, then you would need to restart the computer to get it to get the display back again. To do so without a display press Windows + D (to select Desktop) press Alt+F4 and then press Enter – this will most likely do a Shutdown, unless you recently choose Restart from the Shutdown menu. Then you can after the computer turns off turn your system back on again and the display should be restored.