iTunes Store: Finding missing music and video downloads
If you have (for whatever reason) lost media that you downloaded from the iTunes Store on your computer, here are some steps to try and find the files.
Find files on your hard drive
If the song is still listed in your iTunes library but you don't know where it is on your computer, see this article for steps to locate where it is on your hard drive.
If you can't find the song or video anywhere in iTunes, try searching for it on your computer—Windows users, use Windows Explorer; Mac users, use Spotlight or the Finder. The first step is to search for files ending in .m4p (audio), .m4v (video), or .ipg (iPod games). These are the file extensions for music, video, and iPod game files purchased from the iTunes Store. Sometimes the iTunes database can be emptied without actually having deleted the music files.
Windows users
On the Start menu, click Search.
Click All Files and folders.
In the "All or part of the file name" field, type either m4p or m4v or ipg and then click Search.
If you see the files you are looking for in the Search Results window, you can add them back into your iTunes library.