How can I stop my dog from barking constantly?

I have a one-year-old Shih Tzu who I love but she is honestly driving me insane. She barks at nothing at all. She will just randomly start barking at the wall. We can barely talk in my house as she's so loud. Going to sleep at night is a nightmare as she won't shut up. She also barks first thing in the morning so I have little sleep because of her and she's making me feel exhausted, annoyed and ill because of it.