In the Windows OS file paths are not case-sensitive.

I wanted to identify where in my HTML-documents I have used incorrect case for any file reference so I could migrate to hosts where case-sensitivity would make misspelled references impossible to find.

The enclosed function takes a path eg
D:\VS FISA WEB\SITES\fisa\ MAIN\ES\ACTIVIT Y.HTM
and, if the file exists (not case sensitive), returns
D:\VS...