When you restore an archived class, you see the class card again with your current classes. You can use its posts, assignments, comments, and materials again.
- Go to classroom.google.com.
- At the top, click Menu
. 
- Scroll down and click Archived classes. Note: If you haven’t archived any classes, this option won’t be in the menu.
- On the class card, click More
Restore. - Click Restore to confirm.