How to downgrade iTunes 8.2 without losing your library (Mac)

Method 1: How to downgrade iTunes 8.2 and restore iTunes Library from the backup folder

When you upgrade your iTunes, the previous version of the library is backed up in the "\Music\iTunes\Previous iTunes Libraries\" folder. called "Previous iTunes Libraries". To downgrade iTunes:

1. To completely remove iTunes 8.2, you may follow Apple Support’s article.
   
   If you're familiar with Terminal application, you can simply run the following command in Terminal app to delete iTunes:
   

   sudo rm -rf /Applications/iTunes.app /System/Library/PrivateFrameworks/DeviceLink.framework /System/Library/Extensions/AppleMobileDevice.kext /System/Library/PrivateFrameworks/iTunesAccess.framework /System/Library/PrivateFrameworks/CoreFP.framework /System/Library/PrivateFrameworks/MobileDevice.framework

2. Download and install a previous version of iTunes such as 8.1.1
3. Go to "\Music\iTunes\" folder, Right Click on "iTunes lirbrary.itl" and rename it to "iTunes lirbrary.itl.old"
4. Go to "\Music\iTunes\Previous iTunes Libraries\" folder.
   Select & copy desired backup library (most probably you would use the backup library with the most recent date appended to its name).
5. Paste the backup library into the "\Music\iTunes\" folder and rename it to "iTunes lirbrary.itl".
6. Launch the older version of iTunes

Method 2: How to downgrade iTunes 8.2 and restore iTunes Library using Time Machine
If you have Time Machine, you can invoke it in the finder with the "iTunes Music" folder open, and travel back in time to restore the latest version of the library before you upgraded iTunes.

Please note that songs added to the library since upgrading to the latest version of iTunes will not appear in the library if you downgrade, so you will have to add them manually by dragging them into the main iTunes window.