I'd start with simply downloading afresh and install it. If that fails, you reboot and delete iTunes from Control Panel, then try again.
You only lose what you didn't backup So if you have a backup of your settings, your library and media, you surely lose nothing. But usually an uninstall only uninstalls the program, not your data.
Kees
I was informed of a software update for iTunes and proceeded to download & install. Unfortunately it was unsuccessful.
When I click on iTunes I get error messages. 'The procedure entry point CMBlockBufferCopyData Bytes could not be located in thedynamic link library CoreMedia.dif'
when I click on 'OK' it says
iTunes was not installed properly. Please reinstall iTunes
Error 7 (Windows error 17)
Should I just go ahead and download iTunes afresh or should I delete the existing iTunes program first?
If I do this - will i lose all my music etc?
I would be grateful for any help

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