Can't remember movie name!?

I saw this movie a long time ago and sort of remember what happened but I can't remember the name of it. Basically the movie started out with a guy who was asked to be involved in a project but was told that after the project his mind would be wiped. He does the project, mind is wiped and when he leaves the people give him back his items that he had when he had arrived. Weird things start happening or something I can't remember but basically it turns out that the items he had were clues he had left for himself to figure out what was going on. Please if anybody knows what this movie is please answer!