Why won't iTunes sync music with my iPhone 4s?

Things that I've tried that don't work:
-Clicking the sync music tab and applying it over and over again
-turning off icloud
-syncing it artist by artist
-leaving my phone unlocked while it was syncing
-Uninstall and reinstall iTunes

I don't know what else to do.

Have you added your music folders in iTunes?
File/Add to library (Add your music folder)

Hope that helps.