My screen went black and then went white.

My screen went black and then went white.

I was playing roblox, lagging for a bit but isn’t wasn’t anything out of the ordinary. My screen went black for a second, and then black again for longer. I was sitting there for about 2, or 3 minutes searching up how to fix it, when I looked up, it suddenly changed to a flicker of notepad, I used it to write something, and then white. I don’t know the issue, help please.