Chances are, if you formatted your system or erased a bit of stuff out of your iTunes library, it might not show all the music you had purchased from the store.
There's no need to panic though. Apple does a pretty good job of making sure you can get back all your purchased music on iTunes with just one click.
Since iCloud, Apple has made it really easy to make sure your purchases are stored and you can reclaim them just in case you end up losing the apps, music, books etc. With iTunes, everything is just about a click away.
If you find yourself with an empty iTunes library after, say, a re-installation, you might have to just turn to your purchase history to download all the songs back. Note that this works only with songs that you purchased / download through iTunes. Also, if you purchased a song on the iPhone or iPad, it gets associated to your Apple ID so you can re-download them through iTunes on PC just by logging into your Apple ID.
So, how to get back all your music purchased via iTunes? Here's how:
- Open iTunes on your PC/Mac
- Make sure you are logged in to your Apple ID account in iTunes.
- Under “Store” click on iTunes Store
- From the options on the main menu, tap on Purchases
- iTunes purchases are categorized under music, app etc. Choose Music.
- You can sort the Music through albums, songs, titles and artists etc. Choosing Songs will make things easier.
- You can either click on the Download button against each song you want re-download or if you want it all, click on Download All.
- Wait as all the songs get downloaded to your iTunes library.
That's about it. Once you do this, all your music is re-downloaded.
But you first have to authorize the computer that you are using, via iTunes. You can authorize as many as five computers for the same Apple ID.
Check this out to transfer purchased music from iPhone to iTunes.