How do I get my music back?

Earlier today I syned my iPhone 4S with iTunes. EVerything seemd fine until a few hours later I was in the car and wanted to play some music. I grabbed my phone, opened the music app, only to find that my music library had been dropped from 664 songs to only 34 songs (which were all by the way in the cloud, so i had to redownload them all). When I got home I immediatly hopped on my computer and tried to fix it.

The first thing I did was just try to resync my phone; it didnt work, everytime I tried to sync it then iTunes would say that I only have around .2G left (which should be correct) but them as soon as the sync is about to over it droppes ad says that I have over 4G of memory left, because it didnt sync the songs. Then I tried resterting the computer, nothing; doing a soft reset on my phone, nothing; even restoring the back-up of my phone, nothing is working!

I've tried everything I can think of besides doing an actual full reset on my phone which I would really not like to do. Can anyone help me and please tell me how to get my music backl on my phone. I really need it for something important on Monday. Any suggestions are helpful! Tahnks!