[chaley]

In the situation you describe, where you still have all the books, using CCs "scan for books on connect" option should take care of most of the restore. You would need to tell CC to use the folder on the SD card that contains the books, ensure the scan option is on (settings), then connect as a wireless device. CC will look through the folder and add to it's database all books it finds that aren't already there. It then passes the metadata to calibre in order to get the latest information. This process should be very accurate for epubs that were put onto the SD card by CC.

Other formats depend more on calibre's book matching to ensure that the book on the device is correctly associated with the book in the library. Books that are mismatched will show in calibre's device view without an "in library" check mark. These books will need to be resent to reestablish the linkage.

There are apps that claim to do full backups. I haven't tried any of them.

Although there isn't much data in CC that isn't a copy of what it got from calibre, adding a way to backup/restore CCs database is a good idea. I will add it to our to-do list