JVC Everio Camcorder Memory Problem?

Hey, I have the JVC Everio GZ-MS230BU and it says I've used all the Built-in Memory? I don't have any videos on it and it says I have only 5 minutes to film?? How do I get my memory back? I had 1 hour 5 minutes to use but now it's only 5 minutes. I also have a OPTIMA SDHC 60min HD 4GB SD card but when I put it into the camera it doesn't show up with anymore time. Please help me.