If music doesn't play in iTunes for Windows

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Update Windows

Use Windows Update to ensure that you have the latest Service Pack installed.

Check your computer authorizations

If you can't play a song or video that you purchased from the iTunes Store, you may have exceeded the five computer authorization limit on which to play your music purchases. Once you've authorized five computers (by playing songs you've purchased on them), you won't be able to listen to purchased songs on a sixth computer until you deauthorize one of the first five.

To deauthorize a computer:

1. On the computer you want to deauthorize (make sure that it's connected to the Internet), open iTunes.
2. Choose Advanced > Deauthorize Computer.
3. Select the "Deauthorize Computer for Apple iTunes Store Account" option.
4. Click OK.

Make sure that all of your authorized computers have the latest version of iTunes installed. For example, after purchasing content from the iTunes Store with iTunes 8, you should upgrade all other computers on which you make iTunes Store purchases to iTunes 8.

Shared playlist issues

If you're listening to a shared library or playlist, iTunes will skip any purchased music in the list if your computer hasn't been authorized to play that music.

Older AAC files might not play

If you're trying to play an AAC file that was not created in iTunes or downloaded from the iTunes Store, it might not play. Songs you download from the iTunes Store or import into your library using the AAC encoder are encoded in MPEG-4 AAC format, and will play in iTunes and on your iPod. Older AAC files that you find on the Internet or elsewhere may not play in iTunes.

Check your disc format

If you're trying to play a song on a CD or DVD that you burned in iTunes, make sure that the equipment you're trying to play the CD or DVD on is appropriate for the disc's format. For example, if you burned an audio CD on a CD-RW disc, you can only play it in your computer. If you burned an MP3 disc, it should play in your computer and in special MP3 CD players, but not in standard consumer audio CD players.