To think how many films have been lost - not just through deterioration, but wilful destruction at the beginning of the sound ers...
I think the saddest tale of all lost footage (if it be true) is the missing reels of
Greed: they were originally considered lost since the twenties and the savage cuts made by both von Stroheim and MGM (42 reels down to 23 and eventually 12, or about 145 minutes), but a 1993 book claimed that in the late 50s/early 60s that several reels labelled "McTeague" were discovered in the company's vaults and destroyed because no-one knew what they really were.