"Only the Apollo 11 telemetry tapes made during the moonwalk are missing—and not those of Apollo 12, 14, 15, 16, and 17. For technical reasons, the Apollo 11 Lunar Module (LM) carried a Slow-scan television (SSTV) camera (see Apollo TV camera). In order to be broadcast to regular television, a scan conversion has to be done. The radio telescope at Parkes Observatory in Australia was in position to receive the telemetry from the Moon at the time of the Apollo 11 Moonwalk. Parkes had a larger antenna than NASA's antenna in Australia at the Honeysuckle Creek Tracking Station, so it received a better picture. It also received a better picture than NASA's antenna at Goldstone Deep Space Communications Complex. This direct TV signal, along with telemetry data, was recorded onto one-inch fourteen-track analog tape there. A crude, real-time scan conversion of the SSTV signal was done in Australia before it was broadcast around the world. The original SSTV transmission had better detail and contrast than the scan-converted pictures. It is this tape made in Australia before the scan conversion which is missing. Tapes or films of the scan-converted pictures exist and are available. Still photographs of the original SSTV image are available (see photos). Also, about fifteen minutes of the SSTV images of the Apollo 11 moonwalk were filmed by an amateur 8 mm film camera, and these are also available. Later Apollo missions did not use SSTV, and their video is also available. At least some of the telemetry tapes from the ALSEP scientific experiments left on the Moon (which ran until 1977) still exist, according to Dr. Williams. Copies of those tapes have been found.
"Others are looking for the missing telemetry tapes, but for different reasons. The tapes contain the original and highest quality video feed from the Apollo 11 lunar landing which a number of former Apollo personnel want to recover for posterity, while NASA engineers looking towards future Moon missions believe the Apollo telemetry data may be useful for their design studies. Their investigations have determined that the Apollo 11 tapes were sent for storage at the US National Archives in 1970, but by 1984 all the Apollo 11 tapes had been returned to the Goddard Space Flight Center at their request. The tapes are believed to have been stored rather than re-used, and efforts to determine where they were stored are ongoing. Goddard was storing 35,000 new tapes per year in 1967, even before the lunar landings.
"On November 1, 2006 Cosmos Magazine reported that some one-hundred data tapes recorded in Australia during the Apollo 11 mission had been discovered in a small marine science laboratory in the main physics building at the Curtin University of Technology in Perth, Australia. One of the old tapes has been sent to NASA for analysis. The slow-scan television images were not on the tape."
Ironically, that comes from the Wiki entry on moon landing hoaxes.
In other words, a small amount of the ORIGINAL moonwalk telemetry, of Apollo 11 only, was lost, seemingly in Australia, but not before multiple copies and video recordings of the material had been made.