itunes cant sync only music after i change my id

Hi there Mehta_pooja90,

Welcome to Apple Support Communities.

If I understand correctly, there's an issue syncing music to your iPhone from iTunes on your PC after changing your Apple ID in iTunes.

Can you still play the songs that aren't able to sync in iTunes on your PC? If iTunes isn't authorized to play the tracks, then you aren't going to be able to sync those songs to your device. Try authorizing the computer with the account that was used to purchase the tracks as shown here:

Authorize your computer in iTunes - Apple Support

Also, the article below provides a lot of great information about what to do after changing your Apple ID.

What to do after you change your Apple ID email address or password - Apple Support

Take care.

You're welcome.