If you try to open an assignment but it says the page is "Locked" and/or "Read-only," it's because you've already hit the Turn In button on that assignment.
If it's before the due date, you can "Undo Turn-in" to unlock it using the steps below.
If it's after the due date, you may or may not be able to unlock it, depending on the settings determined by the teacher.
If you try to open an assignment but it says the page is "Locked" and/or "Read-only"...
1. Go to where you would normally open the assignment in Teams:
General channel (left)
then
Assignments tab (top)
2. If you don't see the assignment you want, click the small arrow next to "Completed."
3. Open the assignment and click the purple "Undo Turn In" button.*
Try to open your assignment again.
* If there is no "Undo turn in" button, then the due date has passed.