The eShop is nice, you can buy games from the shop and download them to your Nintendo 3DS. Games are much bigger than ever before and need to be saved to the SD memory card that you can install into your 3DS. But these cards can also break down, how to backup the precious data (and their savegames).
Nintendo has put a guide on how to do this on their website. Along with that comes also the recent update to our beloved console. We are now also able to backup games from within the console itself. We can move or copy forwards or backwards data to and from the SDcard. You will find this in the System menu.
As for the backup of the SDcard, you will need an SDcard reader on your PC (external or internal). Also you will need another SDcard if you want to move data to a new card.
What to do:
Insert the SD card with the Nintendo 3DS data into the SD card slot or the SD card reader/writer.
Open Windows Explorer (for PC) or Finder (for Mac) and access the SD card.
Highlight the data and drag it to the desktop.
Eject the first SD card.
Insert the second SD card into the slot or reader/writer.
Using Windows Explorer or Finder, locate and access the SD card again.
Drag the data from the desktop to the second SD card.
Perhaps we should add some steps in between there though for safely removing removable media option in at least Windows, as removing it suddenly can corrupt files.
Now that you have it on your PC, you can easily just keep that copy for use, write it to another disk or to a CD or another USB memory stick for safekeeping.
Although Nintendo says that they don’t support memory cards greater than 2Gb, most bigger SDHC cards do work in the 3DS and offer you much more space. 2Gb is really fast full of data.
Hope this helps, if not feel free to leave your comment and we will try to help you.