I have posted a few discussions like Pray for Paris a few years ago and a riddle contest a few days ago. I checked back on them and I saw that the page wasn't available. Did Duolingo delete them? If so why? They were completely harmless and not spam at all.
Have you set up a real email address with Duolingo? When a moderator deletes someone's discussion, they will generally message that person explaining why. (Though, staff have given mods the go ahead to not message people over removed lingot posts. Still, some mods will message people anyway as a courtesy.)