Final answer:
The 1977 film 'Star Wars: Episode IV - A New Hope' revitalized interest in full symphonic film scores with its iconic soundtrack composed by John Williams.
Step-by-step explanation:
The film that is credited with resurrecting interest in the full symphonic film score in 1977, when the practice had gone out of fashion, is Star Wars: Episode IV - A New Hope. Composed by John Williams, the score famously combines traditional leitmotifs with a grand orchestral style, drawing from classical and Romantic influences. This approach was a shift from the pop and rock music scores that were prevalent in the industry at the time, and its success sparked a revival in the use of symphonic soundtracks in cinema.