I sent you a big ass email a couple months ago, which must have been deleted when you did your spring cleaning. I'll try to condense it this time. (everyone got a form email if they got deleted, just fyi)
I already have a nonfiction book, published by a now-out-of-business publisher in 2002. I have my rights back. 20,000 copies were printed, of which 10,000 sold. The remaining 10,000 are settling into a new home (small genre publisher) who will store/market/distribute/sell
I did not have a need for an agent before. However, if I want to keep this book alive (with a new publisher), and maybe write another one or two or three, I am going to need an agent now.
What kind of a query do I send when I am not sure what exactly it is that I am wanting to sell?
Agents are not mind readers.
You need to be clear what you want and then write a cogent letter explaining it.
All the agents who talk about helping an author plan a career, and giving career guidance are talking about what happens AFTER they read a query letter and take on a project, not the first step.