Based on below I don’t understand how the B. O. M. Has Nephi chapters if the original translation was lost?? The book of Lehi
Joseph Smith began with the book of Lehi when he was translating the Book of Mormon. It was a record that Mormon had abridged from the plates of Lehi. After he had 116 pages of manuscript that he had translated from this book, Joseph gave the manuscript to Martin Harris, who had briefly served as Joseph’s scribe in the translation of the Book of Mormon. The pages were then lost. Joseph did not retranslate the book of Lehi to replace the lost manuscript but instead translated other related accounts from the gold plates.