Listen to Happy Days: Main Theme (From the Original Score to "Happy Days") online. Happy Days: Main Theme (From the Original Score to "Happy Days") is an English language song and is sung by Dominik Hauser. Happy Days: Main Theme (From the Original Score to "Happy Days"), from the album Television's Finest: Vol. 2 - The 70s, was released in the year 2013. The duration of the song is 1:14. Download English songs online from JioSaavn.