iTunes update has changed the directories of my files by itself

Hello,
I encounterd a really strange problem after updating iTunes to its newest version 11.4; but let me explain better.
I opened iTunes and a box pops up saying that there is a new update ready to install. Then I pressed ok, the update started to be installed (it took a few minutes!) and as it finished it asked me to restart windows.
I restarted windows and a box appeared before loading the usual desktop screen: it was saying my version of Windows 7 is not authentical (?!). I chose the option "remind me later" (or whatever), the desktop appeared and I firstly noticed the wallpaper was the "default" one of Windows 7 (it substantially removed my wallpaper).
But things get worse the more I navigate on the pc: appearently all the files have been removed. And with that I mean ALL the files, not only the music library, but also the documents, the videos, ecc.

I was quiet desperated when I went on the "Computer" screen, and I saw that the space on the disk was the same as before the iTunes update. Then I navigate through Computer/C/Users and I noticed there were THREE folders: Administrator, Administrator.CCT-20140822GTQ and Public, the first two both with a "lock" symbol on the icon.
If I go in the first folder, Administrator, I can see and access all the files in the usual folders (Documents, Desktop, Download, ecc.). In the "Administrator.CCT-20140822GTQ" folder there is nothing, and it's like my laptop navigates/shows me that folder instead of the "Administrator" folder.

Luckily the files have not been deleted, but it's a little uncomfortable to reach them through navigating to the folder as I described. Please help me understunding what happened and how to fix this issue!

Thanks in advance, and sorry for my bad english.

Up!