No particular song in mind? If you wish to browse in the popular music sections, these call number ranges may be useful. The stack areas are on the 2nd floor of the Music and Performing Arts Library.
M1630.18-popular music of the U.S.
M1741.18-popular music of Great Britain
M1503-piano-vocal scores of musicals and operas, in order by composer
M1507-M1508-excerpts from musicals and operas
M1527.2-motion picture music