Uncontrolled Substance (lost original recordings of Inspectah Deck album; 1995)
Inspectah Deck (real name Jason Hunter) is a rapper from the New York borough of Staten Island. He is a member of the 9-man group called the 'Wu-tang Clan' based in the same area. After the group's initial release 'Enter the 36 Chambers' (1993), the members of the group set out to release their own albums in the following years.
Whilst members of the group such as 'Method Man' and 'GZA' released Tical (1994) and 'Liquid Swords'(1995) respectively, Inspectah's solo album was not to be released until 1999. This album, although still being named Uncontrolled Substance is vastly different from what the original version was planned to be.
The Lost Album
Whilst the recordings for Inspectah's album was done as early as 1993 and a release was slated for 1995, a combination of his label Loud/RCA having bigger releases to promote, signing on other big-name rappers and eventually going under meant that the release had to be delayed to 1997, by which time he would have released it under new Sony ownership of the label.
After this initial setback, worse news came. He then learned that his producer and fellow clan member RZA's apartment had been affected by a flood. This meant that all of the material produced for the album was rendered damaged beyond repair. RZA estimates around 300 different songs were lost in this flood, and despite Inspectah's best efforts to restore the water damaged floppy disks they were being kept on it was to no avail. This agonizingly meant he had to start again from scratch, and eventually released the new rerecorded Uncontrolled Substance in 1999, which can be found easily online. 
Due to the original copies being damaged beyond restoration, none of the recordings for the initial release exist online or otherwise. Inspectah Deck went on to say in a 2015 interview with VLAD TV that his original vision was entirely different to the released one, with songs such as 'Not your average flow' and 'Blowing up the spot' among the lost recordings.