iPod classic is not recognized in iTunes . it erased all my music and now want all music back

It may help to uninstall your current copy of iTunes and install the previous build. See the very bottom of Troubleshooting issues with iTunes for Windows updates - Apple Community for download links.

Once you get iTunes to see the iPod see Sync your iPhone, iPad, or iPod using your computer - Apple Support for advice on syncing.

See also Corrupt iPod Classic - Apple Community to check the health of the iPod's hard drive.

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See Recover media from an iPod - Apple Community. Depending on what has happened your media files may still be present in hidden folder from which they can be copied off, or you may need to use an undelete utility to reclaim them.

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Assuming you are running Windows try iOS device not showing in iTunes for Windows - Apple Community. Despite the title the same steps may help. If you installed iTunes using the Microsoft Store you may want to try a direct download from apple. com. It may also help to use a slightly older build.

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