The recovery software gave the extension of .HTM for S11Loop's file in another thread that he started, after testing 1 renaming to JPG he managed to see the file preview, so thus he requested for help on batch renaming.
And you're probably right on using 'ren', I must be thinking of the UNIX command 'mv' instead. My bad.
No worries, now I get the full picture too. For command-prompt usage, either the "ren" or "rename" will rename the file name/extension. OT a bit, the "move" command actually has a hidden usage, that is to rename directory names!