Norton Internet Security is an important program because it protects your computer from viruses. It also scans documents, emails, and websites for threats that you might not be aware of. If you have downloaded Norton, and it won't open on your computer, it means you have one of several problems that might prevent Norton from protecting you.
Right click on Norton and see if you can access "Properties." If you can, click on it and read if there are any errors with the program. If so, click on the errors and attempt to clear them.
Click on Add/remove programs if you cannot see or clear any errors. Find this under "My computer" or "Control Panel." Scroll through the programs that are installed, and click on Norton. Remove it. Then, put in the installation disk or go to the site where you downloaded Norton. Re-download the program in order to clear any errors with your original program.
Contact Norton Internet Security Troubleshooting on the site listed in resources, if you are getting a specific error message. If you type the error message into the search bar, you'll get specific instructions about how to fix the problem.