My Micro SD Card (2 GB) won't show up on my computer?

I'm using it with a Patriot Memory Adapter and the little green light that's next to the slot on my computer lights up but nothing popped up and when I tried to manually open it through "My Computer" all the drives said "Please insert a disk into Removable Disk (H:)" Or whatever drive it is. Please help I really need to get some files on this card. I'm running Windows Vista and It's an HP.