Board Thread:Skyrim/@comment-108.217.193.85-20150102004834/@comment-1251315-20150102005122

This bug can happen to a range of quest items, not just Black Books from Dragonborn. There's one thing you can do to check: go back into Cidhna Mine and find the evidence chest (or whatever it's called). At that point you have two paths:
 * 1) If the books aren't there and you play on PC, just spawn them in using the console: the id's can be found on the respective pages on the wiki
 * 2) If they're not present and you dont' play PC, you should reload a save before you played the quest "The Forsworn Conspiracy" and just play through all black books to get what you need, then lose the books.