Restore backup didn't work - Iphone 4?

I have an Iphone 4 and I wanted to sync it with a new Itunes library. So i backed it up and then synced it and it deleted all my music. Then when I restored the back up it went through with no errors, but i still didn't have my music back on my iphone or in the itunes library. Please Help I HAVE So MANY SONGS AND I CAN't REMEMBER THEM All TO RE-DOWNLOAD!

You can download this freeware( Syncios) to have a try. When it is installed, it can sync in its iTunes library with the backup musics in iTunes. Then you can just try just a few steps to restore you music~