Good question!

If you click on the assignment again on the course page (same link you clicked to submit the assignment first), now once it is closed and graded you should see a "Review" option as in the screenshot below:

Clicking on "Review" will allow you to review your submission, including answers and solution ideas available since the assignment is closed.

For future reference, note this requires you submit something for the assignment (even a blank assignment), so if you ever don't have time to complete an assignment, please try to submit something so you'll have access again after it closes.