You might be trying to sign in to Google Classroom with the wrong account. Check that you’re using the email account connected to Classroom. You sign in to Classroom with one of these accounts:
Note: You must have an active Internet connection to sign in.
If you can’t sign in with the correct email account and password, maybe your school’s administrator doesn’t automatically activate Classroom for new students and users. Contact Us.
If your school uses G Suite for Education—Ask your teacher to send you a new class code. If the new class code doesn’t work, ask your teacher to contact the school’s admin.
If you’re a student using a personal Google Account outside of a school—Ask your teacher to send you a new class code.
A class code consists of 6 or 7 alphanumeric characters. For example, hihmgrk or g5gdp1.
Note: You only use the class code once to enroll. You don't need to re-use the class code.
Your teacher turned off posting for that class. Ask your teacher for more information.
You can’t undelete a post. However, your teacher can see all your deleted posts.
If your school uses G Suite for Education—Your school’s admin might have turned off Gmail for students. Ask your teacher to contact the admin.
If you’re a student using a personal Google Account outside of a school—See Gmail Help.