Check if you have stored music in the phone memory, that is, the C drive of your phone. Music tracks in C:\Data folder are backed up and restored to your phone during the software update to Nokia Belle. But if you have stored music tracks in any other folders in the C drive, they are lost during the software update. If you have DRM protected music tracks in your phone, note that you lose the licenses during the software update to Nokia Belle. After the update, you need to relicense all the copy protected music tracks you have on the phone.
This topic is valid for:
Nokia C6,Nokia E73,Nokia E7,Nokia E6,Nokia X2-01,Nokia 808 PureView,Nokia 700,Nokia 5310