2001: A Space Odyssey (lost deleted scenes of science fiction film; 1968)
2001: A Space Odyssey is a 1968 film directed by Stanley Kubrick and starring Arthur C. Clarke. It originally debuted in USA. The plot of this film follows mankind's biggest moments of progress, leading up to space travel and the struggle between mankind and machines. 
There were about 17 minutes of cuts made to the film by Stanley Kubrick before its release. Multiple sources include details of what these scenes pertained to. These cuts seem primarily to alter the pacing of certain scenes rather than removing scenes altogether.
On October 10th, 2017, an article came out from BloomsMag that all 17 minutes of the cut footage has been found in a salt mine vault in Kansas.
- Some shots from the "Dawn of Man" sequence were removed, and a new scene was inserted where an ape pauses with the bone it is about to use as a tool. The new scene was a low-angle shot of the monolith, done in order to portray and clarify the connection between the man-ape using the tool and the monolith.
- Some shots of Frank Poole jogging in the centrifuge were removed.
- An entire sequence of several shots in which Dave Bowman searches for the replacement antenna part in storage was removed.
- A scene where HAL severs radio communication between the "Discovery" and Poole's pod before killing him was removed. This scene explains a line that stayed in the film in which Bowman addresses HAL on the subject.
- Some shots of Poole's space walk before he is killed were removed.
These deleted scenes were recently found by Warner Bros. in a salt-mine in Kansas, but most have suggested that there's no plan to release a complete version of the film since Kubrick himself made these cuts. As such, these deleted scenes are not "lost" per say, but they are not likely to resurface to the public at the moment.
- IMDb summary of deleted scenes themselves Retrieved 08 Sept '17
- DIY Magazine article about the deleted scenes being found Retrieved 08 Sept '17
- News coverage of the announcement of scenes being found Retrieved 08 Sept '17
- The BloomsMag article that talks about the footage being found. Retrieved 11 Oct '17