At last, I checked processes in task manager, and found that when I try to launch the game with the launcher, it creates a javaw.exe process for a split second, and the process immediately disappears. Then I have checked the firewall, to see if it conflicts with Minecraft or Java, and it doesn't. Cleaning the registry for leftovers from possibly corrupt Java re-install didn't help either. Unfortunately, neither of these fixes did anything. I have tried a couple of usual fixes, such as re-downloading and re-installing both Minecraft and Java (64-bit) itself. There was no strange behavior of any kind prior to that. Slightly over a month ago, Minecraft suddenly stopped working on my computer.