My Bloody Valentine's second album, Loveless, is considered to be the greatest album of the shoegazing movement. It founded a lot of the tropes and formulas that are present in modern-day shoegazing music. While there are a few missing tracks from the sessions that the band has never released, it isn't the only thing from the album that is lost.
Part of what makes Loveless such an enigmatic album are the vocals. They are sunken way down in the mix (for those of you who don't understand, it means the vocals are quieter than most of the rest of the music, uncommon for popular music). The lyrics were barely pronounced, and it was done that way on purpose. What's strange is that Kevin Sheilds and Belinda Butcher, the two vocalists, spent more time on vocals than on most of the instrumentals. Most albums produced in such a manner would have very omnipresent lyrics and vocals, but here it's the opposite. The result: the real lyrics to Loveless are an honest-to-God mystery.
While "lyrics" are available online, they're all just guesses people have made from live recordings, reading the mouths of the singers on stage and in videos, and listening really carefully. The leaflet in the album was very minimalistic and did not feature lyrics; just an insert with album credits and that's it. The band has yet to confirm if any of the online-submitted lyrics are correct. For a while they joked about holding a contest to see who could guess all the lyrics right, offering a cash sum to the first person who nailed it perfect. Sheilds then made it an official contest, and apparently nobody has yet to crack the lyrical code this album holds. Odds are we will more than likely never know what the true lyrics are until every last member of the band is long dead.