retrieve data from incomplete responses

If you close your survey, a popup will ask you what you want to do with responses in progress. You can choose to record them as incomplete. 

When you download your data you can look at the columns Finished and Progress to separate them from completed responses. 

Thanks @ahmedA! Unfortunately, the survey has already been closed. And as I have selected (delete incomplete responses” in my setting when publishing the survey, the respective data has not been saved. But I thought perhaps there is a way to reconstruct/retrieve them somehow. Maybe they have been saved somewhere that I just cannot access?

In that case, you'll have to get in touch with Qualtrics Support. They may be able to help you.