It depends on what you mean. If you had use the Captivate recording process to create the slides, the background image for the slide should still be in the library. However, any elements that were also added to the slide would be gone and need to be re-added and repositioned.
Thanks for the clarification - I see now that the deleted background image can easily be restored to the project via drag/drop. And I see that the original elements for the slide in question are NOT available once deleted. What do you suppose is the rationale behind this design? Do you suppose having the background image and its associated elements retained upon delete a redundant or useless feature?
I never really thought about that. I've used Captivate for many years and it never occurred to me that if I removed a slide that Captivate should somehow remember and track any objects on that slide. To contrast, Microsoft PowerPoint has been around MUCH longer than Captivate, and it behaves in a similar manner, no?
If a slide has images on it, the images are still in the Captivate library along with the background image. Other elements are easily available via the Insert menu or toolbars. I could see where it could be a programming nightmare trying to keep tabs on elements and know not only which slide they should be on as well as any settings they had and exactly where on the slide they were placed.
You might consider submitting an enhancement request at http://www.adobe.com/go/wish