A man Without Words, by Susan Schaller.
Schaller was an American Sign Language interpreter when she first met a deaf 27 year old man, Ildefonso. He could mime some basic needs, it seems, but had no language per se. Schaller worked with him intensively and eventually he had a breakthrough that things had names...
Schaller spent a fair amount of time tracing down other "languageless" people, and the language therapists who work with them. She also, many years after working with Ildefonso, found him again, and through him discovered a community of men who were also languageless.
This is a fascinating book, a quick and easy read. It's not availabe in eformat, but used copies are only a few dollars.
There is a lot more that I wish she would expand on. She does go into the difference between "languageless" people like Ildefonso and the "wild" children who have absolutely no language at all. I'd like to know more about these "wild" children, and more about how "languageless" people think (it's incomprehensible to me how someone can think without words - I know that autistics like Temple Grandin say they think in pictures. I'd love to know more about that.)
My next book is one Schaller mentions in her book, The Language Instinct by Steven Pinker. Maybe that one can answer my questions about the relationship between language and thought.