If one or all of your Premium Content items stop working it's because something happened to your ccmerged.package file. The file is located in the DCBackup folder. Either the file was accidentally deleted or has become corrupted. It is easy to fix this!
You can do a factory reset of your game (this will take a long time if your store items aren't backed up and you have to re-download everything) OR you can go to this site and download a new ccmerged.package file to put into your DCBackup folder. Easy peasy!
http://nonasims.wordpress.com/2012/05/17/dcbackup-ccmerged-package-and-your-premium-content-items/
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1) Do a factory reset of your game, which takes seconds, by dragging your The Sims 3 folder to your desktop.
2) Redownload ONLY your PC. In some cases this may take longer depending on whether the item's page shows that you own it. For example, I can't download just the wood fire oven because the website doesn't show that I own Monte Vista. So if I want to redownload and install the oven, I need to redownload and install the entire world from my purchase history. But I can redownload all of the rest of my PC individually.
3) Install your PC using the launcher.
4) Open DCBackup. Copy that ccmerged file to somewhere safe. This is your new, clean, uncorrupted ccmerged file.
5) Replace your The Sims 3 folder in your Electronic Arts folder with the one you dragged to your desktop.
6) Replace your ccmerged file in your DCBackup folder with the ccmerged file you just created.
Done!