Windows Media Player includes some of the most popular codecs, like MP3, Windows Media Audio, and Windows Media Video. However, it doesn't include the codecs required for Blu‑ray Disc files, FLAC files, or FLV files. If something isn’t working in Windows Media Player, you might not have the right codec on your PC. The easiest way to fix this problem is to go online and search for the codec you need.
Not all Windows Media Player playback problems involve codecs. If your problem is codec-related, you'll probably receive a message like "A codec is required to play this file" or "Windows Media Player encountered an error." In this situation, follow the steps to learn more about the missing codecs. If it turns out that it's not a codec issue, see Troubleshoot audio problems in Windows Media Center for help with audio problems and general playback issues.
Here are answers to some common questions about codecs.