cp <répertoire cible> <répertoire de sauvegarde>
If the recover button was present on the GRAMPS family tree, click it. All should work again. If you notice you lost information, or the repair button does not work, then do the following. If recovery worked, but you do not like the result, backup this data and place your backup taken above back in its original position. You now have again the bad family tree to work on. Next, obtain the bsddb recovery tools, see your distributions package search page. The program is called db4.6_recover, where 4.6 might be an older or newer version number.
Run this tool as follows:
That should do the trick, and allow GRAMPS to load the family tree. If not, then start a ticket on the gramps bug tracker.
=== Implement more security ===