You can recover those questions only if you have downloaded the survey as word file. If you have not downloaded that questionnaire as word file, then you will have to manually type in the questions with its options. Data once deleted can not be retrieved
Once you questionnaire is downloaded, then you can create a new survey and upload that survey questionnaire in the word file and then you can save those questions in the question library . Once added to the question library , you can add those question in the survey which you got deleted in the first place.