If you want the stuff which originally came on the Kobo back, check out the Kobo forum's sticky thread on
how to replace a possibly corrupted sqlite db with a fresh copy.
However, it does require wiping all the other stuff you may have put on your reader since then and reloading afterwards, and since you had problems before, it may not be worth your time.
As for which editions Kobo used, I'm pretty sure they're the exact same as the ones found via their special Free eBooks listing at the top of the site. Whenever I've seen a promo picture of the Kobo displaying the cover of a "classic" while in sleep mode, it's been the same image as the covers shown in the Free eBooks section.