integration of media files

[Moved from Your WordPress which is NOT a support forum.]

i have a none-wrdpress site
i want to make a wordpress version of it
i am trying to get posts with its images, which i uploaded from ftp to wp-content/upload/articles
i made a query and get them to wp_posts table with type attachment and with full path of them (https://domain-name/wp-content/upload/articles)
and attache to posts
in wordpress admin media library it shows that this attachment is belong to this post but it show blank image about it and when edit it no image dimension or preview appear.
i have more that 8000 post and i cannot d this manual so please i want a tool to do that