Answer:

The answer is that the Book of Enoch, also known as 1st Enoch, certainly has not been lost, and neither has it been forgotten. It was not taken out of the Old Testament because it was never part of the Old Testament.  Anyone who likes can read the translated text any time they like.  Here is a link to the text of the Book of Enoch:  http://scriptural-truth.com/images/BookOfEnoch.pdf

In fact, the Ethiopian Coptic Church still has the Book of Enoch in its Old Testament canon.  This is the only significant Christian group which includes Enoch.  It has been in their canon from ancient times, so the book has never been “lost.”  It was “lost” to Europe from the early Medieval period until the late 1700’s when a Scottish explorer James Bruce brought three manuscripts to the UK, from which it was translated into English in the nineteenth century.