Unable to open very old Freehand / Illustrator Files

Hi, I'm unable to open some important old vector files that I have dating back to around 2001. They would have been generated in Freehand but are showing with an Illustrator Icon. I've tried adding the .ai suffix but that hasn't helped. I've also tried File > Open without any luck either. No joy with any other adobe cc programs either. Does anyone have a fix for this ?   Thanks