While errors like this may look like they'd be specific and give a clue to the problem. In most cased they don't. Since you say you can't access the program. The first suggestion would be to reboot your computer and see if that helps. If not you'll have to do a repair or reinstall.
First, it is very important to state in each post which version (and service pack level) of Civil 3D you are using. Many customers simply put that in their profile signature so that they don't have to keep typing that in.
To add more to the reply already posted:
If you can reproduce the error consistently, open a subscription support case with Autodesk so we can investigate and resolve.
Before you do that, it will be helpful if you submit a crash report ("CER") which usually follows a fatal error. In that, be sure to use your email address, relevant comments. When you open your support case, let them know that you submitted a crash report so they can correlate the two.