Sometimes students end up switching their account to a teacher account. In some cases, when they first create their account, and they just click teacher instead of student. In other cases they find that if they go to account settings, they can change their account to a teacher account:
They do not get access to any teacher data when they do this, but it does mean they can't see their assignments. It's a pretty simple to switch back. In the student's account, you can go to Classes > My Account > Switch to Student Account
Once they switch their account back to a student account, they should have access to all their assignments once again and won't have any data lost.
If there is data lost, please email us at firstname.lastname@example.org or the chat box on the bottom right hand corner.