I had a strange one today, I haven’t loaded iTunes for a while (my iPod holds most of the stuff I want to listen to), but my son needs some party music for his first birthday.
So I loaded iTunes and the shorcut referenced a location that no longer exists?! A quick check showed there was no iTunes.exe!
Rather than uninstall and reinstall and lose all my settings, a quick Control Panel -> Programs and Features -> iTunes -> Repair did the job splendidly!
Hope this helps someone!