Errors when loading sketches

I had made some changes to a sketch and then I did a Save As in order to keep the original file untouched. The IDE complained about characters in the file name but there was nothing but letters and numbers in the file name I used.

So now I get the above message when I open any sketch. How do I fix this?

Rename the sketches so they don't start with 0 to 9, and the folder they are in to match.

Rudy216: The IDE complained about characters in the file name but there was nothing but letters and numbers in the file name I used.

You missed the "and it cannot start with a number" part of the message.

Thanks. Yes I missed that part. All cleared up now.

What confused me was opening a properly named and still getting the same error.