images don't show up!

i am trying to upload pictures gallery to post, the pictures show up nicely in the post back end but when i post it nothing is showing up, not even the featured picture which is one of the gallery pictures.

in the post itself the thumbnails show up as usual but when you click on them there is an no entry sign like this: https://snag.gy/POCmw.jpg
** i added the red shapes to the screen cause the pictures contains pornography, the red shapes have nothing to do with the site itself**

that problem is from some reason ONLY with those pictures, its not happening with former posts NOR with new one i made up for test. it also didn’t happened when i uploaded file to the “upload” directory trhough ftp client and added the picture to the media library through “add from server” plugin. i did the same with the current pictures.

i also tried to reupload the pictures as PNG instead of jpeg but the problem remains the same.

what is going on here?!