Somehow just corrupted my excel file!

I've just spent all morning working on a xlsx spreadsheet. When I'd finished, I went to save the file as a csv so that I could import it where I needed to, but this is where I did something wrong. I'm really not sure what I did, but I did not end up with a csv file, and now I can't access the file at all! I receive this message:

"Cannot open file because the file format or file extension is not valid. Verify the file has not been corrupted and that the file extension matches the format of the file."

Any help would be greatly appreciated!

Hello Fred45,
What is the full name of this file, including the extension?

Regards
Kingali

Hello Fred45,
What is the full name of this file, including the extension?

Regards
Kingali