Check first that the Function key that kills the brightness hasn't been turned right down by accident. If you have another monitor, and a cable, try moving the display to that screen and use the Function key with a screen icon on it to switch over.
If all taht fails, the screen would need replacing but the data can be transferred to another PC if you remove the hard disk and slave it to that other machine. Details if needed. (
Is the screen black, but emitting a backlight? If no backlight from the LCD, can you connect an external screen and get a picture? (If no to both of these, it could be hardware failure.)
There is no backlight, I can't plug it into an external screen as I'm currently away on an overland trip in Scotland for photography. The software is about 6gb to download on to my surface tab and I only have mobile data to run off. It's just I need to upload new files for members that meet the new GDPR rules but they will have to wait till next week.