Why is all of my music greyed out on my iPhone 4?

I haven't been able to sync my iphone with my iTunes music for several months now, which is getting increasingly frustrating, and as the holiday season approaches, I really need something to tune out all the holiday music >:-|.

To avoid all the obvious questions: I am running the newest version of iTunes (11.0) and iOS (6.0.1), I have over 4 1/2 gb free on my phone, I have unselected and selected different folders of music (being sure it can all fit in space available on my phone), attempted to auto-fill free space and not, restarted iTunes, my computer, my phone, shut down all the apps, connected and disconnected my phone to my computer, and connected and disconnected the wi-fi sync. Changed settings to sync only checked songs, and manually manage music and back, I have attempted a sync every step of the way.

The music shows that it is syncing, the blue bar of music content volume shows that it's filling up, then at the end of the sync it disappears again. My music folder on my phone has all of the songs I want to sync listed but greyed out and unplayable.

Reading through a bunch of other discussions I have found a few unsuccessful solutions and have attempted this: http://support.apple.com/kb/HT1747, as reccomended, but my efforts were thwarted with a "iTunes can’t be modified or deleted because it’s required by Mac OS X." message, so I didn't get very far.

I cant seem to make podcasts sync either, but books seem to sync fine.

I did to a restore when the problem first happened, but am afraid to do it again as my iCloud is also acting up (another battle for another topic...) and I'm afraid I will lose everything.

Am I missing something really obvious? Why isn't this working???