Hi Yigit,
The image in your png is just the content. It does show, however, if you select edit then the screen is blank and does not let you update or edit content. I can send you screenshots however you can also test this. Log in, select a page, try to edit the content section. There is a draft page available for testing. Please help!
I deactivated all of the plugins and still cannot edit the content. I have since re-enabled the plugins. Can you think of anything else we can try?