This song, originally called "Christmas, Why Can’t I Find You," was written by James Horner for the 2000 movie How the Grinch Stole Christmas. It was first performed by Taylor Momsen, who played Cindy Lou Who in the movie. A different version was later co-written by James Horner, Will Jennings and Mariah Carey, where it was given its more popularly-known title, "Where Are You Christmas?"
https://music.justinreeve.com/where-are-you-christmas/
