Missing Product Images

Nothing has been changed, no updates done recently with wp or any plugin.

But many product images in the woo commerce shop suddenly have gone.
They have been replaced with the placeholder image.

Also I can see the image files are missing from the server.

I find it strange because if I manually delete any image files from the server that are currently being used as product image on the site, then those products still have a connection with the deleted image and still tries to display them but cannot find them,

However in this issue I am having, the files are gone from the server, and each product in woocommerce no longer has any connection with the original image. So just re-uploading the image is not enough to bring them back. I need to either manually go to each product in wp admin and re-upload or restore the whole database.

Any ideas or suggestions on what might have caused this. It seems strange to me almost as if the database has changed or corrupt and also the relevant images are missing from the server. I am checking ftp logs ect and there is no sign of deletions.