Whenever I launch minecraft it goes onto the mojang loading screen and then freezes.

As I said previously, when I open the minecraft launcher and launch any version of minecraft, it goes onto the mojang loading screen, then loads for a few seconds then freezes and says "Not Responding". I've waited hours to see if it was just a time-related bug, but it still didn't load. I have deinstalled and reinstalled minecraft almost ten times now, and each time the same thing happens.