In Colossians 4:16,Paul asks them to read a letter he wrote to the Laodiceans. Is this book available anywhere or is it permanently lost?
That is one of the easier questions I have gotten. The answer is that this letter is lost. It is possible, but very unlikely, that this letter will surface. Not likely, because it is not mentioned in early Christian writings, which is evidence that the early church did not preserve this letter. It is likely that Paul wrote many letters which never made it into the New Testament. Were any of these letters inspired as well? That is a fun question. It is believed by scholars that Paul wrote at least one more letter to the Corinthians, as he mentions in his first letter. Probably Paul wrote dozens of letters that we do not have. I assume that Peter and John also wrote letters which are not in the New Testament. But we, as Christians, accept on faith that the ones God wanted included in the New Testament have ended up there. Sorry, but that is the best we can do. This is a fun question to think about and to speculate on, but that is all we can do when it comes to other letters which Paul wrote.