How come when I go to see the stories for example, I can not go back to my classrooms?
I'm not staff, but staff will need more information when they are reading your comment. Are you a teacher or a student? What platform are you using (ios, android, desktop). Which browser are you using (Chrome, Firefox, etc)? Duolingo on Desktop is optimized for the Chrome browser, btw. Sometimes using another browser will cause things to perform less than optimally.
Can you describe your situation with a bit more detail? What happens when you try to get back to your classroom? How exactly are you prevented from returning?