Did you have outstanding correction notes from editors when you deleted? I think this causes problems in the system, as your quizzes still "exist" because of the correction notes. I have a feeling the only way to sort it out is to "throw yourself on the mercy" of the editor(s) who were dealing with the deleted quizzes and ask them very nicely to help you out. Then hope like mad that they will...
It is better to open your eyes and say you do not understand, than to close your eyes and say you do not believe.