Hello black spot,
It sounds like you are concerned with what may happen to the iTunes media files on your computer if you reinstall iTunes. iTunes keeps the media files and the application files in different locations so that you can uninstall and reinstall iTunes without losing your content.
By default, the iTunes media files are stored in the following locations:
- Windows XP: C:\Documents and Settings\username\My Documents\My Music\iTunes\
- Windows Vista: C:\Users\username\Music\iTunes\
- Windows 7: C:\Users\username\My Music\iTunes\
- Windows 8: C:\Users\username\My Music\iTunes\
You can find more information about locating your iTunes media files in the following article:
I am not sure what error message you are getting or what version of Windows you are using, but I found a few articles that might help with the situation you are experiencing::
Thank you for using Apple Support Communities.