... I bought some music on itunes, ...
Download Past Purchases
- Sign in with the Apple ID that you used for the original purchase. See which Apple ID you used to download an item.
2) See if the content is available for redownload. Previously purchased items might not be available if they're no longer on the iTunes Store.
File > Devices > Transfer Purchases
More Info Here > http://support.apple.com/kb/HT1848
...the music dissapeared and my itunes balance wasnt restored.
To Contact iTunes Customer Service and request assistance
Use this Link > Apple Support iTunes Store Contact