After trying to update iTunes which failed using the normal process, then you started to get error messages;
“Microsoft visual C++ runtime library
C:\program files (x86)…
An application has made an attempt to load the C runtime library incorrectly”
To fix this:
Go to Control Panel > Add or Remove Programs (Win XP) or Programs and Features (later)
Remove all of these items in the following order:
- Apple Software Update
- Apple Mobile Device Support (if this won’t uninstall move on to the next item)
- Apple Application Support
Reboot, download iTunes, then reinstall, either using an account with administrative rights, or right-clicking the downloaded installer and selecting Run as Administrator.
The uninstall and reinstall process will preserve your iTunes library and settings, but ideally you would back up the library and your other important personal documents and data on a regular basis.