The Mexican director reveals the incident happened while he was trying to decide whether to take the reigns on a major superhero blockbuster or concentrate on making his acclaimed 2006 fantasy Pan's Labyrinth.
Del Toro was distraught and appealed to a higher power to bring back the book and help him make the huge career choice.
He tells Canada's TheStar.com, ""(The book contained) all my drawings, all my notes for Devil's Backbone, Blade II, Hellboy and Pan's Labyrinth. I was up for a huge Marvel superhero movie and I was prepping Pan's Labyrinth, and I was considering which movie to do. I felt very sad... I always say everything has a meaning. I spent the night thinking what does it mean? It means I am about to lose myself if I take the big movie. I said, 'I'll do Pan's Labyrinth and now can I please have my notebook back?'... at that moment the phone rang (and it was the cab driver).
""I think he thought he had the notebook of a psychopath. Hellboy hadn't come out yet, and here are these anatomical drawings and drawings of guys with horns and tiny handwriting.""
The driver returned the notebook and Del Toro handed him a large tip. He also went through with his decision to ditch the unnamed superhero film and prioritise Pan's Labyrinth - a move which led to his triple Oscar win in 2007.
The Spanish-language movie won Academy Awards for Best Art Direction, Best Cinematography and Best Make-up, as well as three British Academy of Film and Television Arts (BAFTA) Awards.