I'm afraid I don't understand what this sentence means. Are your old files still on your "original" 4 GB card, or is that a completely different card at this point?The only previous SD card I have is the original 4gb one. It wouldn't have helped in my predicament exactly. The other one i upgraded to i messed up in a ham-fisted early attempt to resolve this issue (basically i formatted it, used windows to try to copy everything back, it didn't work. Yes, I was dumb, it was like 2 in the morning).
I don't think I've ever read about something quite like this happening before. Usually when something happens to SD cards, everything except TWiLight Menu and the pre-installed titles are lost (i.e. everything not installed to the internal NAND memory). It is unusual to somehow still have titles installed from the eShop but not ones installed by FBI. While you could start deleting things I emphasize that other mysterious things could very likely go wrong later.