Are you able to launch AutoCAD now? Or it doesn't start at all?

If you are not able to start it you have to be sure that your AutoCAD was updated with Service Pack 1 in order to reset AutoCAD with this method:
you need to launch AutoCAD from Dock by holding Shift key on keyboard and clicking on AutoCAD icon (you need to hold Shift for at least a few moments after you click on icon). This helps in the case when you cannot start AutoCAD normally

Maxim