Then don't waste the time or money to sue.

I'm sure it would have been.  However, you're operating on the assumption that the person who wrote the song in question took the lyrics from your "book."  Given that only 200 copies were sold, that seems unlikely.  In order to sue successfully for copyright infringement, you will have to prove two things:  similarity and access.  Do you have any evidence that the songwriter saw your "book"?

If you want to sue, consult with an attorney because no one who hasn't seen your book or who doesn't know the song can offer you much of anything that will be useful.  If you don't want to sue, then move on with your life.

Then contact the management of the artist and, if different, the songwriter and some folks with the record label.