Re-install iTunes

To reinstall iTunes, the first thing you have to do is uninstall iTunes from you computer.
If you have the iTunes application open, close the application first before proceeding.
Go to Control Panel > Programs. Select the iTunes program and click on the uninstall menu. This action will uninstall iTunes from your computer.

Install iTunes again. To install iTunes, download the installer here. After downloading, run the iTunes installer. This will guide you through the steps to successfully install iTunes. When you are done with the installation, open the iTunes application to verify that it has been installed properly.