If assignments seem to disappear from your LaunchPad after their due dates have passed, your instructor may have the LaunchPad set up so that only assignments due in the future are visible to you.
Please note that depending on how your instructor has set up your course, you may not be able to complete past due assignments for a grade. Some assignments may allow you to work on them after the due date for review purposes, but they will not be graded. If this is the case, you will receive a small pop-up with a warning like the one pictured below.
Click on the Show Past Due link on your LaunchPad home page, to the right of the Assignments heading. This will reveal past due homework assignments (and the units that those assignments are located in).
Use the scroll arrows to move from month to month
Using the up arrow button at the top left of the calendar, you can scroll to prior months to see your past due assignments.