Could you evaluate more on what actually happens when you start the game? I would suggest trying to update your launcher to the latest one. If you already have, try uninstalling and reinstalling your launcher and minecraft. If that still doesn't work try contacting Mojang themselves and working out the problem with them! Hope I could help!
Could you please explain a little more? If not I would recommend re-installing the launcher? If that doesn't work try updating your launcher? If that still doesn't work I recommend to contact Mojang and work out the problem with them, Because it might be a bug in the version that they need to correct.