Follow these steps to make sure all images and shapes in your PowerPoint presentation are visible:

1. Check that you are viewing the correct slide.
2. Ensure the image is not placed behind other objects.
3. Verify the image is not behind text.
4. Make sure the transparency of the image is set to 0%.
5. Check if the same image has been inserted multiple times and one is hidden.
6. Check the zoom level of the slide to allow for better visibility.