Hello and welcome to justanswer, My name is ***** ***** i will be assisting you today,
I'm sorry about the issue, what error do you get exactly when you try ato open autodesk ? it is
license system error:-15570 or license system error: 30?
Can you try to uninstall it using revo uninstaller program, first download the program from this link : http://www.revouninstaller.com/revo_uninstaller_free_download.html and run it.
Now select Autocad program and click on Moderate mode, and wait a few minutes. Once it has completed creating the system restore point and analyzing your application, it will launch the default uninstaller utility of the autocad program.
after that it will proceed to detect the obsolete and remained registry keys. Select All button, all the items will be selected. To complete the removal, press the Delete button.
Now reboot and reinstall autocad.
Let me know the results please