Hello rosebud26,
Thanks for using Apple Support Communities.
For more information on this, take a look at:
Removing and reinstalling iTunes and other software components for Windows Vista, Windows 7, or Windows 8
http://support.apple.com/kb/ht1923
While it's highly unlikely that you'll lose any contents of your iTunes Library when following these steps, it's always a good idea to ensure that your iTunes library is backed up. If you're unsure how to backup, follow these steps.
Best of luck,
Mario