How to fix Excel file format errors in iCloud Drive

I have an Excel file in my iCloud Drive in a .xlsx format. This is a file I use daily, and I made the mistake thinking that since it is in the cloud it is backed up. When I try to open this file today I get the Alert saying, "Excel cannot open the file 'Cycling.xlsx' because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file."

I have a PC and I tried opening it there with the 'Open and Repair' option, but no luck. I tried opening it on my iPhone, and iPad, but no luck. I tired to duplicate the file, change the name, and open it, but no luck. Is there any ideas out there?

[Re-Titled by Moderator]