Aren’t there inspired books that we’ve lost?

Answer:

Just because a book is mentioned in a book inspired by God, it is not necessary to conclude that the referenced work is also inspired. For example, Paul quotes a Cretan prophet: "One of them, a prophet of their own, said, "Cretans are always liars, evil beasts, lazy gluttons" (Titus 1:12). This does not mean the man was a real prophet or was inspired. He was cited to prove Paul's point that even Cretans knew they had problems.

A book can also be referenced by a different title than the ones we use today.

The Book of the Covenant (Exodus 24:7)

This is referring to Exodus 20:1-23:33 that Moses wrote down. "So Moses came and told the people all the words of the LORD and all the judgments. And all the people answered with one voice and said, "All the words which the LORD has said we will do." And Moses wrote all the words of the LORD. And he rose early in the morning, and built an altar at the foot of the mountain, and twelve pillars according to the twelve tribes of Israel" (Exodus 24:3-4). While it is no longer a separate book, we still have its content.

The Book of the Wars of the Lord (Numbers 21:14-15)

The book is cited to confirm one of the boundaries of Israel's territory. Whether this was an Israelite book or a Gentile book is not determinable. For the latter, it would be cited as evidence that others also recognized Israel's boundaries. Nothing leads to the conclusion that this was an inspired book.

The Book of Jasher (Joshua 10:13 and II Samuel 1:18)

This is probably a reference to a storybook. See The Book of Jasher for details.

The Manner of the Kingdom (I Samuel 10:25).

God told Samuel to warn the people what it would be like to have a king. "Now therefore, heed their voice. However, you shall solemnly forewarn them, and show them the behavior of the king who will reign over them" (I Samuel 8:9). This was told in I Samuel 8:11-18. I Samuel 10:25 tells us that Samuel wrote these same words to be a covenant document and placed them before God. Therefore, we have the words that were in this document.

The Book of the Acts of Solomon (I Kings 11:41)

This is a reference to records of Solomon's reign. Notice that no authors are mentioned. There is no indication that it was an inspired record. Like most kingdoms, records were kept of Solomon's reign. The author of this section of I Kings is letting us know that what was recorded was just a summary of the highlights that God thought important for us to know about Solomon's reign.

The Chronicles of King David (I Chronicles 27:24)

This is the book we refer to as II Samuel. It is referring to II Samuel 24:12-15 specifically.

The Book of Samuel the Seer, the Book of Nathan the Prophet, and the Book of Gad the Seer (I Chronicles 29:29)

This is referring to the book we now call II Samuel. It is a composite work of three prophets and covers the acts of David.

The book of Nathan the prophet, the prophecy of Ahijah the Shilonite, and the visions of Iddo the Seer (II Chronicles 9:29)

These works cover the reigns of Solomon and Jeroboam, which are found in I Kings 1:1 to 11:43

The book of Shemaiah the prophet, and of Iddo the seer (II Chronicles 12:15)

This one focuses on Rehoboam, which is the next section of I Kings from 12:1 to 14:31.

The Annals of the prophet Iddo (II Chronicles 13:22)

This treatise covers the reign of Abijah and is found in I Kings 15:1-15:8

The annals of Jehu the son of Hanani (II Chronicles 20:34)

This writing covers the reign of Jehoshaphat. Notice that this one specifically mentions that the annals are recorded in the larger collection called the book of the Kings of Israel. This is found in I Kings 22:2-50.

The writings of Isaiah (II Chronicles 26:22)

This covers the reign of Uzziah, which is in II Kings 14:21-22 and II Kings 15:1-7.

The writings of Hozai (the seers) (II Chronicles 33:19)

This covers the reign of Manasseh, which is in II Kings 21:1-18.

Writings of the Prophets (Matthew 2:23)

Matthew points out that this move also fulfilled prophecies. But notice that Matthew is not quoting one particular prophet, he is giving a general summary of what multiple prophets have said. The name Nazareth might be derived from the Hebrew word for "branch." There are numerous prophecies concerning the Messiah being called the Branch, such as Isaiah 11:1. The best case, however, is that the region of Galilee had a poor reputation (John 7:52) and the town of Nazareth had an even poorer reputation (John 1:46). The Hebrew word netzer, from which Nazareth is derived, refers to the small twigs that are worthless (Isaiah 14:19; John 15:21). Such was deemed an appropriate name for a small village of little use. There are several prophecies dealing with people despising the Messiah, such as Isaiah 53:2-3 and Psalms 22:6. The Messiah's coming from a despised area was foretold in Isaiah 9:1-2.

A prior letter to Corinth? (I Corinthians 5:9)

Paul did not say a prior letter but referred back to what he wrote previously. In other words, the earlier part of the same letter (I Corinthians 5:2). See Judging Christians for details.

A brief letter to Ephesus? (Ephesians 3:3)

Again, this is referring back to his brief introduction to the topic in Ephesians 1:9-10.

The Letter to Laodicea (Colossians 4:15)

This is a reference to Philemon. See The Prison Letters for details.

Jude's Writing (Jude 3)

This is a reference to the letter Jude was writing -- the book of Jude

Enoch (Jude 14-15)

Jude quotes Enoch but does not say the quote comes from a book. See The Book of Enoch for details.

Conclusion

There are a few extra-biblical writings mentioned in the Bible, but a mention of them does not mean they are inspired writings. The vast majority of references are actually references to other parts of the Bible. The claim that God has not preserved His Word is not proven. The claim that there is more material needed to complete the Bible is not proven (besides contradicting what the Bible states about itself).