I can't play online multiplayer all of a sudden

Recently I started having a hard time joining realms and playing online multiplayer. I haven't been having this issue until yesterday. It keeps saying "You cannot play on Realms because of how your Xbox Live account is set up." I didn't change anything and nobody has accessed my account at all. Can you please fix this bug because it's really starting to become frustrating. AND NOTHING IS WRONG WITH MY CONNECTION AT ALL. So can you please help me?