Listen to I Don't Know Why (I Just Do) online. I Don't Know Why (I Just Do) is an English language song and is sung by Nat King Cole Trio. I Don't Know Why (I Just Do), from the album The Nat King Cole Trio - The Complete Capitol Transcription Sessions, was released in the year 2013. The duration of the song is 2:46. Download English songs online from JioSaavn.