Last I heard, 'Annie get your gun' was a lost movie. That is to say that all copies of the original movie were destroyed in a fire and were therefore unavailable for broadcasting or purchase. However, it seems that there is a 50th anniversary copy available to buy through Amazon.com and older copies on video! This leads me to ask, do you know of any movies that have actually been lost and what are the circumstances? Any additional info on the AGYG story would also be appreciated!
I'm sure there are loads of silent classics that are "lost", and certainly a lot of older "Dr Who" is no longer available. The only "lost" movie I can think of doesn't quite fit into your category, but there is a "Fantastic Four" movie that was made on the cheap in order to retain the rights. As a big budget movie is in the works (one day...), the current owners bought the rights to the unreleased cheapy and will not let it be shown.