Realms wont work

So I just purchased around a realm. With ten people allowed at most. And it was working fine. Until today. When it would not let anyone on. Or connect to it. And even after restarting my Wi-Fi. It would not work. And when I tried to install a backup version. Of the same realm from the night before. It would not work. So I'm trying to fix this problem. As soon as possible. Because I just purchased this realm. And I want to get back on it.