Hopefully I am not just asking a question that has already been answered. I cannot find any reports of the same problem

I am in the process of finishing the campaign. I am almost to the end of the story, and suddenly I cannot get the game to boot up. Steam tells me it is starting properly, then just shuts down. No error message, no code, nothing.

This is frustrating considering I am probably an hour or two from the end. I've verified the installed files, and I even tried uninstalling and reinstalling the game completely. Nothing seems to help.

How can I get the game to work again?