Thirteen Reasons Why by Jay Asher

Clay Jensen returns home from school to find a strange package with his name on it lying on his porch. Inside he discovers several cassette tapes recorded by Hannah Baker–his classmate and crush–who committed suicide two weeks earlier. Hannah’s voice tells him that there are thirteen reasons why she decided to end her life. Clay is one of them. If he listens, he’ll find out why.
This is also a Netflix series.