I tried to update my Itunes to the news version and now it will not open it says it was installed incorrectly I need to know what to do so I don't lose all my music

try with this one

uninstall all the apple application S/w like Quicktime, Bonjour,

apple Device Support, Apple Auto update, Itunes etc from your pc,

Reboot it

Now download a fresh itunes from apple and try installing

Reboot it

If you are having Problem in uninstalling any of the apple application

try 'revo uninstaller' and uninstall all the apple applications

mentioned above