This is Memento. Memento is a 2000 American psychological thriller and neo-noir film written and directed by Christopher Nolan. Its about a man, suffering from short-term memory loss, uses notes and tattoos to hunt for the man he thinks killed his wife.
"Nuovo Cinema Paradiso" (Giuseppe Tornatore, Ennio Morricone's score is sensational. My son was the same age & looked just like "Toto." This movie kills me, every time. Don't let the subtitles scare you away, watch it in Italian.