The "Allow automatic export to grades" box may not be checked. This can be found on the Assessment tab while editing the quiz.
Make sure that the item is marked as visible. This can be done for created quizzes under Manage Quizzes. Summit tests and lessons are done from Content.
No worries, this can be done it just requires a certain steps to be taken. Navigate to the Quizzes Tutorial page and watch Edit Quiz Questions After Assigned & Scores in the Gradebook video.
Have no fear! You can restore a deleted attempt. Navigate to the Quizzes Tutorial page and watch Restore a Deleted Quiz Attempt video.