To troubleshoot why your PowerPoint presentation is not displaying a picture after cropping, here is a list of items to look into:

1. Check to make sure the cropped image matches the crop boundary on the slide.
2. Adjust the slide size if needed.
3. Check the shadow setting in the picture format menu.
4. Make sure all pictures used in the presentation are saved as the same file format.
5. Re-upload the image if it appears to have been corrupted.
6. Verify your printer settings.
7. Restart your computer and try again.