Changing the extension is easy, but it will more than likely render your file unusable. Changing the extension doesn’t actually change the format; it just gives Windows inaccurate information about what type of file you’re trying to launch more often than not resulting in an unusable file.

Some file types can be converted. Text file (.txt) to an HTML file (.htm) so that you can view it in a web browser is possible. . Similarly, converting audio filed i.e. .wav file to an .mp3 file

To change a file name extension, first ensure that file name extensions are visible. Then, right-click the file you want to change and click Rename. Delete the file name extension, type the new extension, and then press ENTER.