when was it released?
July 3, 1985
Back to the Future
"Back to the Future" was initially scheduled to release in May 1985. It was pushed back to June 21, the earliest Zemeckis could have it ready. The production delay following Stoltz's replacement pushed it back to July 19, and later to August. After previewing the film, Sheinberg was impressed. He moved the release date forward to July 3, giving it an extra 16 days of theatrical screentime during the industry's most profitable time of the year. 
how many parts to back to the future Two parts is it a movie or a tv series? Movie
wiki:11601477
Back to the Future [SEP] Release
After previewing the film, Sheinberg was impressed. He moved the release date forward to July 3, giving it an extra 16 days of theatrical screentime during the industry's most profitable time of the year. This would offer approximately 100,000 extra screenings worth an estimated $40million. Sheinberg said he also wanted to avoid the negative perception of films released later in the summer period, instead of early like other blockbuster films. The change required renegotiations with theater owners to secure screens in an already crowded marketplace. In some cities, it was legally required that exhibitors be shown a film prior to purchase.