If it's a thesis the chapter is for then permission isn't so important AFAIK i.e. you can reproduce copyright material for fair use. But if it's for a book or a paper the rules are more stringent.
Personally if it's for your thesis I'd say you've tried to contact them, to be fair, but if the organisation no longer exists and you can't trace the person you can't do much more than that, so just use it as it stands.
But if it's for a paper or a book you can't use it.