There is a backup file in your Virtual Villagers folder, but it won't be as current as the one that you deleted. The savegame files are Isola**.ldw (where ** is a number). The single-digit numbers are your "primary" savegame files and are numbered 1-5 (corresponding to the player slots). The two-digit numbers are the "backup" savegame files, and are numbered 21-25. If you rename the backup file that corresponds to the one that you deleted, you will be able to recover that game to a previous point in play.
To safeguard your games in the future, you may want to periodically back them up manually. The savegame files are ordinary files that can be backed up in a safe location of your choosing. Just remember to pause the games first, or you may be greeted by an unpleasant surprise if you ever need to restore one of them.
