Pictures deleted

I have runned the plugin on my website, but now a lot of my pictures have disappeared. The are still in the media folder, and they are there as a thumbnail, but not if i click on the product:
https://roundsom.nl/nieuwste-producten/
https://roundsom.nl/product/boston-sc-240-1-jack-speaker-kabel/

If you follow the link you will see that the product picture is still available in the first link.
In the second link you don’t see a picture. When you click on the square with the question mark it will appear.
How do i fix this without having to update thousands of my product picture’s?

Thank god this is a test run, but my new website has to go online in May.