Bobby Hebb "Sunny" (1966).

Written and proformed by Bobby Hebb. It is one of the most covered popular songs, with hundreds of versions released. BMI rates "Sunny" number 25 in its "Top 100 songs of the century".
"Sunny" has been covered by, among others, Boney M, Cher, Georgie Fame, Johnny Rivers, Stevie Wonder, Frank Sinatra with Duke Ellington, Ella Fitzgerald, the Electric Flag, The Four Seasons, the Four Tops, James Brown, Wilson Pickett, Les McCann, Dusty Springfield, and The Alex Trio featuring David Wise.
Hebb wrote the song after suffering a double tragedy - a national loss followed by a personal one: On 22 November 1963, the day after US President John F. Kennedy was assassinated, Hebb's older brother Harold was killed in a knife fight outside a Nashville nightclub. Hebb was devastated by both events and many critics say that those events inspired the tune. Others claims Bobby wrote the song for God.
"Sunny" was recorded at Bell Sound Studios in New York City and released as a single in 1966. It met an immediate success, which resulted in Hebb touring in 1966 with The Beatles.