Hello and welcome to JustAnswer, I look forward to assisting you today. The reason for the problem is, your camera will not recognize anything over a 2GB card. What is the part number you are referring to?
Just so you are not confused, we are not affiliated with Panasonic. We are an independent tech support service. The memory card slot is located under a hatch on the right side of the camera as you look at it from the rear. Open the hatch and push in on the card and it should pop out. You have not damage the camera in any way. All you need to do is use a 2GB card in place of the one you have and you should be okay.