Q: i have problem to sync my music after updated my phone

Greetings Ruby C, 

Thank you for using the Apple Support Communities!

I understand that you are having an issue syncing your iPhone to your computer. The following article gives a great overview on syncing and how it works. 

Sync your iPhone, iPad, or iPod touch with iTunes on your computer using USB - Apple Support

If you are having a more specific issue like your iPhone not showing up as a device in iTunes or some specific content not syncing as expected, please elaborate more on your question so that we can provide the best support possible. 

Best!

Thank you for replying with this information.

To troubleshoot and resolve an issue where you see a message that the sync session failed to start, please read over and work though the steps outlined in the following article.

If you can't make an iTunes backup of your iPhone, iPad, or iPod touch - Apple Support

Have a great day!