[SOLVED] Itunes wont’t start after update

i updated my itunes and after restart of my pc itunes says this:
"iTunes cannot run because some of its required files are missing.
Please reinstall iTunes."
I am on windows 7
What can i do?
and if i reinstall will i lose my music library?
thanks for help.
Answer #1
C:\Users\Username\Music\iTunes
Move the entire folder somewhere safe. Uninstall then reinstall iTunes. Close iTunes, delete the new iTunes folder, move back the original one, start iTunes, go to File > Add Folder To Library, navigate to the iTunes folder, add folder.
Done!
Answer #2
You can just install without uninstalling the already existing one and try If that doesnt work then back-up using the above said method and uninstall and then install again