What I expected was that after clicking the 'PLAY' button the download will start, the game will open and I may be able to play but what actually happened was that a message came saying that the minecraft game has crashed!

I opened the Minecraft launcher. What i expected to happen was that after clicking the 'PLAY' button, the download will start and the game will open. But what actually happened was that after clicking the 'PLAY' button I received a message in the launcher saying that unfortunately the game has crashed. How can this happen? I am not understanding what to do. Please help me resolve this issue.