The DLC's are within hidden folders, Users\UserName\AppData\Local\Microsoft\Xlive. If there's a Windows.old folder with salvaged files, your DLC is probably in there. Also, you could search, including hidden files and folders, for Anchorage.ESM and you should be led to it all no matter where they went. Once you've found it all, Ctrl+A, Ctrl+X, then Ctrl+V the content to your Fallout 3\Data directory and all should be ok.