On the navbar, click the Activities menu, then select Quizzes.
On the Manage Quizzes tab, from the More Actions button, click Restore.
On the Restore Quizzes page, if any quizzes in the course have been deleted, they will display in a list along with when they were deleted and by whom, and with a button to restore a selected quiz. Click Restore.
Click Manage Quizzes to return to the Manage Quizzes list. The quiz you restored will display in the quiz list. Restored quizzes automatically have any associated quiz attempts that were already taken, statistics, and scores for those quiz attempts restored as well. Links to grade items are not restored. Learn about how to Associate a Quiz with a Grade Item.