Itunes folders

A few days ago I updated my phone the new 16.0 when I plugged in my iPhone into my MacBook Pro it said my phone needed to be updated after doing this I noticed that several of my music folders disappeared. I am a fitness instructor and these folders contained my music for the 3 formats that I teach so now I no longer have them showing in iTunes on my phone. They are still showing on my MacBook in iTunes but will not sync to my phone so I have access to them. How can I retrieve those folders again so I can teach my classes?