This problem takes a bit to explain, so please bear with me.
I wanted to upgrade my 4GB Lexar SDHC card to a 16GB SanDisk SDHC card for my 3DS.
The walkthrough process on the Nintendo site said I should put my first SD card into my computer and "drag the folder from the first SD card to the desktop", and then "drag the data from the desktop to the new SD card".
However, it wasn't that simple. When I tried to move the data from the first card to the desktop, a message popped up that said "some files could not be copied because they are unreadable", and this message popped up over and over, each time I tried to move the "Nintendo 3DS" file to the desktop. I tried taking the SD card in and out, thought maybe my computer was having issues reading it, but no dice.
Finally, I opened the Nintendo 3DS file and copied each and every item to my desktop manually (took quite a bit of time), and then I copied that file into the new SanDisk SD card with no issues. Until I put it in my 3DS and turned it on. My 3DS acted like this was a brand new, totally blank card, and didn't register any of the data whatsoever.
So, I tried plugging in my old SD card to get the data again, but my computer popped up with "This disk is unreadable", and by the time I managed to fix THAT issue, I found out the original SD card was apparently now blank, and my data had been deleted from it completely.
Luckily, I still have the folder labeled "Nintendo 3DS" on my desktop with all of the data in it. Unluckily, the new SanDisk SD card won't read this data as a whole.
I did manage to move my game backup data from the file to the new SD card, and it shows up on my 3DS in the "back-up save data" section, but I won't know if that actually worked until my games redownload.
I also have the issue of Animal Crossing: New Leaf. I downloaded a digital copy of that, and AC:NL doesn't have the option for backup save data. I have not yet redownloaded the game to my system. I don't want to until I figure out if I can save my previous data or not.
So I'm currently left with a "Nintendo 3DS" file on my desktop with a bunch of data in it, backup saves on the new SD card in my 3DS (that I do not know will work for sure yet), and a struggling hope that I can salvage my Animal Crossing data.
So. Anyone have any ideas about what I can do to move the data from the file to the new SD card? Anything helps, thanks!