Published Posts Not Appearing

My published posts aren’t appearing. Just started today with a scheduled post that never went live. In trying to figure out what’s wrong, I marked the previous published post that was appearing back to Draft status. Now it’s disappeared too! Situation is critical as site is most time sensitive. As I said, all previous posts appeared just fine. Last one never went live, then when I tested a second by putting it back to draft mode and republishing, it doesn’t appear in posts either. Help!