Visit the new AutoCAD Support, Revit, Inventor and other pages. They are available in English now, with additional languages coming.
Documentation: How-To, Help Files, Tutorials, New Features, Getting Started, etc.
Troubleshooting: Product Support content, workarounds, product use strategies and known solutions to typical issues
AutoCAD Support Page: http://www.autodesk.com/autocad-support
Don’t forget the RSS Feed for Support and Updates: Product Support, Updates & Service Packs