Earlier, I ran into a little sd card crisis with my 3ds but I managed to fix it. You can read about that here: https://gbatemp.net/threads/11-2-o3ds-small-w-luma-a9lh-not-booting-with-sd-card.456654/
I was only able to backup my saves for Animal Crossing New Leaf, Streetpass Mii plaza, and...