While you're downloading music you've purchased from iTunes, occasionally something could go wrong that interrupts the download. Maybe your computer freezes or the power goes out, shutting off your computer off. The good news is that you haven't lost these incomplete downloads forever. You can recover music already purchased from iTunes.
Click the store menu and select "Check for Available Downloads."
Enter your iTunes username and password. iTunes will search the iTunes store for any downloads that were not completed and resume downloading them. If you're able to now download the music you purchased from iTunes, then you are done. If you aren't able to continue downloading the music you purchased from iTunes and can't find the music in your iTunes library, proceed to Step 4.
Click the store menu and select "View My Account."
Click the button that says "Purchase History," which is located near the middle of the screen.
Click the "Report a Problem" button, which you can find near the bottom of the screen.
Find the songs that didn't download and click the "Report a Problem" link near the right side of the page.
Choose the problem from the "Problem" dropdown menu. Look for the one that most closely describes the problem you experienced while downloading the music file. If you want, type out comments that further explain the problem. Click the "Submit" button. Apple will respond to you shortly.