Imported Books showing inaccurate page counts on iPhone

Yesterday I wanted to read before bed and what did I find? In a 1000 page book, which I had already read 30%, there were 5 first pages left. I checked other books from my library, the same thing, almost all the books were cut to 5 pages. Please help me figure this out! The books had bookmarks with notes. I didn't understand what happened.

[Re-Titled by Moderator]