Sorry to hear about the trouble you are facing while launching Illustrator. CS applications have been discontinued and is no longer compatible with today's operating systems. Could you please confirm which operating system you are working on?
We can can try resetting the preferences. Let us create a backup and then reset preferences.
Close all Adobe applications.
Go to locations
Rename Adobe Illustrator, com.adobe.illustrator, Adobe Illustrator CS6 and Adobe Illustrator CS6 Settings folders to Adobe Illustrator.old, com.adobe.illustrator.old, Adobe Illustrator CS6.old and Adobe Illustrator CS6 Settings.old
Launch Illustrator from the Creative Cloud.
Resetting preferences will remove all the custom settings and Illustrator will launch with default settings. This way all your old settings will be saved in .old folders and Illustrator will recreate new folders with default settings.