Some of my DLC has disappeared! Help! [Xbox 360]

There are several troubleshooting steps you can take to get your DLC back.

Troubleshooting #1: If the tracks are downloading and storing on your hard drive, but are not populating in your game, you may need to clear your song cache. This deletes the pre-stored "song list" that your game loads and instead requires it to make the list from scratch using the songs stored on your console.

• From the Xbox Dashboard, go to My Xbox -> System Settings -> Memory, then choose the device where you have your Rock Band 3 data saved. From there, go to Games -> Rock Band 3 and locate the file ";Rock Band 3 Song Cache." Delete this file.
• When you relaunch Rock Band 3, it may take a bit longer to load all of your DLC than usual, but the song list will be rebuilt and all your music should show.

Troubleshooting #2: Delete the songs from your hard drive and re-download them. You can redownload them from your Purchase or Download history, or by locating the tracks in the Rock Band Music Store or Xbox Marketplace. Make sure you're signed into the account that purchased them. If the tracks are no longer showing as purchased in your history, you'll need to contact Microsoft Customer Support to see what's up with your account.

Troubleshooting #3: Have you updated your console or hard drive recently? If so, make sure you've migrated your account and licenses so that your previously purchased music and exports can be played on your new console. If you have any questions about how to migrate your account and licenses, contact Microsoft customer support.