If you have accidentally deleted your presentation all of your texts, sound files, and links to external webpages will be lost. You will have to input and format them again.
However, all of your images will still be in your Image Gallery, so you don’t need to reload them from your computer. Place your cursor where you want to insert the image and use the Insert Image tool in the editor. Choose “Image Gallery” rather than “Upload”. Mark the image you want to Insert and click on OK.