No, once deleted a form cannot be retrieved.
If you are referring to the response data that users submit to your form you may be able to retrieve them using the History tool. Open your form in FormsCentral and go to the form's View Responses tab. In the lower right corner of the window you will see a clock icon. If you click on the clock you will be presented with a timeline of your form. Pick the point that corresponds to when you think the data was there.