Hello R.U. Sure,
Thank you for becoming a member of the Apple Support Communities and for creating your first post! We’re glad you’re here and look forward to hearing more from you! :-)
After reading your post, it sounds like you may be running Windows XP or Windows Vista. If this is the case, you will first need to uninstall iTunes and all of its related components in the correct order from your computer. To complete this process, please follow the steps in the Steps section of the attached article.
Remove and Reinstall iTunes and other software components from Windows XP - Apple Support
Once removed, if in fact your computer is Windows XP or Vista, use one of the following two links to download the latest supported version. Included are links for the 32 and 64 bit versions.
iTunes 12.1.3 for Windows (32 bit)
iTunes 12.1.3 for Windows (64-bit)
If you are running Windows 7 or later, use the next attached link to download the latest compatible version of iTunes.
iTunes - Download iTunes Now - Apple
Please reply with further information about your situation or to let us know if this information was able to help you resolve the situation with iTunes. We are here to help and want to make sure iTunes is working as expected.
We’re looking forward to your future participation in the Apple Support Communities!
Have a great day!