No music but space used! (iPhone)

Tonight I plugged my iPhone in to my computer to sync. I instantly realised there was a problm as none of my playlists were appearing in the devices drop down. I then went into the music, videos and podcasts folder and nothing there. I checked on the iPhone and in the iPod there is no data.

This is completely bizzare. How could all my music just dissapear like that??

On top of this, I can't re-sync the music because the capacity is already used. No it's not!!

I am using the latest software/firmware version and have had no other problems on this scale.

Hopefuly someone can help with how I can reset it without losing all my contacts, messages etc. Is this a problem you have heard of before??

Many thanks.

I assume you've rebooted the phone? Do you sync your entire library to the phone, or just a playlist?

Yes I have tried rebooting a couple of times.

I sync all my music, a selection of podcasts, a couple of video playlists. Just realised I also had a rented movie on it that is now gone.

Does this help?