Re-establishing the iTunes Library on a New Computer

Did you copy the entire iTunes folder to the external drive, or the iTunes Media folder?

If the latter, copy over the bits you left behind and arrange everything so that the iTunes folder contains the library files, and the Album Artwork & iTunes Media folders. You are best placing the iTunes folder at the root of the drive.

Once everything is on the external drive you can connect it to the new machine. Press and hold down shift as you click the icon to launch iTunes and keep holding until prompted to choose or create a library. Click choose, then browse to and open \iTunes\iTunes Library.itl on the external drive. Or, if there is room, you can copy the entire iTunes folder into your user's Music folder and operate it from there.

tt2

See Make a split library portable for some more background. Uninstalling & reinstalling iTunes doesn't change anything. You need the complete library, not just the media. You either put the iTunes library folder where iTunes is currently looking for it, or press and hold down shift as you launch iTunes so you can point it at the correct library file.

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Generally if syncing doesn't work as expected take the following steps:

1. Backup device.
2. Restore as a new device.
3. Restore the backup made earlier.

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You would do this only if the library on the computer has all of your content. Backing up the device will store all of the personal data associated with each app on the device. For media this includes the selections of content in terms of playlists etc. When you restore all of the selected content should come back to the device, with no greyed out items. If there is a chance that you don't have all of the content, or you've not managed to recover the original library completely, see Recover your iTunes library from your iPod or iOS device.

tt2

Sounds like you got something wrong. You should not have had to add anything to the library, so you shouldn't have managed to create duplicates.

Apple's official advice on duplicates is here at the link you've posted: Find and remove duplicate items in your iTunes library. It is a manual process and the article fails to explain some of the potential pitfalls such as lost ratings and playlist membership, or that sometimes the same file can be represented by multiple entries in the library and that deleting one and recycling the file will break the other.

Use Shift > View > Show Exact Duplicate Items to display duplicates as this is normally a more useful selection. You need to manually select all but one of each group to remove. Sorting the list by Date Added may make it easier to select the appropriate tracks, however this works best when performed immediately after the dupes have been created. If you have multiple entries in iTunes connected to the same file on the hard drive then don't send to the recycle bin.

Use my DeDuper script if you're not sure, don't want to do it by hand, or want to preserve ratings, play counts and playlist membership. See this thread for background, this post for detailed instructions, and please take note of the warning to backup your library before deduping.

(If you don't see the menu bar press ALT to show it temporarily or CTRL+B to keep it displayed.)

The most recent version of the script can tidy dead links as long as there is at least one live duplicate to merge stats and playlist membership to and should cope sensibly when the same file has been added via multiple paths.

tt2

Make sure the device is backed up on the new computer.

Check that iTunes agrees that there is no content when you look at Device > On My Device > Music.

In the image above the greyed out line are failed transfers from an earlier attempt to sync. Those tracks wouldn't show on the device, and repeated syncing didn't fix it. I had to uncheck all such tracks, sync, then check again before they would sync.

Check the sync selections under Device > Music to make sure you still have content selected to sync.

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