IPhone question: my music seems to have disappeared...?

When I click on the iPod link on my phone, there is no music in there. I’ve had my iPhone for more than a year (original iPhone version) and never had a problem like this.

When I plugged my iPhone into my computer this morning, it told me that 4.46 GB of memory are taken up by “Other.” This is exactly the amount that used to be taken up by my music. When I tried to sync, I got an error message saying there isn’t enough capacity to add my music on there. I wonder what that “Other” is that is taking up 4.46 GB, and how to fix it. I’d much rather not reset and lose all my contacts. Any advice?