Update the players firmware over the Internet. Copy protection schemes change and sometimes an update is needed with a new movie. Disney films seem most affected.
Ensure the movie is in a format your player supports. If its a 3D or 4K disc, the player must support that format.
Is the movie from another country? Most players and movies are locked to a specific region of the world and must must match. A player in North/South America will not play a disc sold in other parts of the world, unless it is region free, which is not very common. 4K movies did away with region codes.
You could have a bad or damaged disc. Some players do better than others with marginal discs. Does the disc work in other players?
If the above are all match and movie still does not work after that, you may be stuck. I have a 2 Sony BD players, same model (living room and bedroom) that will not play 'The Hulk' Blu Ray , even after a few firmware updates. I tried friends copies, 3 discs, same problem. Both discs are in perfect condition. It plays in a PS4, PC, and other Blu Ray players, even other Sony players, just not the particular model of BD player I have. I have to use the PS4 to play it.