I updated my MacBook Pro 13" (mid 2010) to Yosemite and my iPhone 5 to iOS 9.2 and I can no longer figure out how to add music to and from my iTunes to my iPhone. It used to be as easy as dragging music to my phone when it was plugged in to my laptop and hitting delete on songs I no longer wanted on my iPhone playlist. What happened? Can someone help me please I can't listen to these same 100 songs anymore! 😉
iPhone 5, iOS 9.2
Do you have iCloud Music Library turned ON? You may, if you subscribe to iTunes Match or Apple Music. You can check on your iPhone, Settings -> Music -> iCloud Music Library (ON/OFF switch). If you have iCloud Music Library turned ON, your iPhone accesses iCloud for songs, not your iTunes library on computer.
Also, if the iPhone is currently set to automatically sync from an iTunes library, you cannot add content manually ("dragging music to my phone when it was plugged in to my laptop"). To set it to use manual loading for music, select the iPhone in iTunes to see its Summary settings screen. There is checkbox for Manually manage music and videos. If that box is not checked, checkmark it and click Apply.
Mote info: Move content from iTunes on your computer to your iPhone, iPad, or iPod touch - Apple Support
Syncing music from iTunes to iPhone
