Cure for black screen

I had the problem about 3-4 years ago and got my computer guru on the problem.  He did a "system restore," going back to about  2014 when I started playing geoguessr.  It now works on Firefox and that's enough for me.  Hope this is helpful.  Please don't ask me for details;  I really don't know any and I'm 77 with very little background in computers.