Images Not Displaying in Media Library, Images Not Displaying on Website

Dear Community, Dear Support,

I have problems on my subsides (2) that I think is not plugin related. Images are Not Displaying in Media Library and Images are Not Displaying on Web(sub)site. Physically all images are on their right location. I can see the images clicking their web address. Internal addresses in WP are not working for the images. Media Library is not showing the images and clicking on their links to view results in 403 page.

Switching to the default WP- theme and switching of plugins does not change the issue. The site has not been moved either. It was a working situation. From my cpanel I restored the files and dbases to june 1st ( a working situation) to quickly resolve the issue, but helas, no results.

I spend two days surfing Google and I am lost. Does anyone came across this behavior already

Kindest regards and thanks for somebody turning me in the right direction, Dirk.