New Songs Not Syncing to iPhone 5?

Okay i'm stumped - just updated my phone and itunes to see if that would work but my new songs still won't sync to my phone. My phone is syncing to iTunes - it backs up, etc. But it will not load my new songs.

Any ideas?

I never sync any of my Apple devices to put music on it. Instead my iTunes is set for manual management of music and video. I almost never have problems putting music on my iPod and obviously much fewer than those complained of in questions like yours which are posted here in the thousands - including loss of music to put songs on my iPod.

Manual management is just clearly superior in every way and it works on iPods, iPhones and iPads both new and old. I've tried it on first generation nanos, iPod 4, iPad 3 and iPhone 5

You enable manual management by bringing up sidebar in iTunes (ctrl S if you don't have it up already) and clicking on the iPod tab. The main window should show you the main summary for your iPod. The box for the manual management option is at the bottom of the page (it's probably already checked).

That's basically it. Now you can just drag the songs from whatever folder they're in in WIndows and drop onto the iPod tab on iTunes sidebar.

Every time you update iTunes, you need to reboot your computer.