half of all the "Add new" pages stopped working!

Hi,

Ok, so I logged into my account and decided to publish a post, but the SEO plug in (WordPress SEO by yoast) is no longer working, I can see it there on the page but I can only see the Title but the rest is gone.

Now I tried to move it, like I could before (change it’s position, minimize it etc..) but I couldn’t and then I clicked on the screen options on top and deselected it but it was still there, I deselected everything but nothing was affected.

when I use to add a featured image it use to open a popup for me to select an image from, but now when I click it it takes me to a new page and even after I select the image it gives me a white screen.

There is a plug in called “WPBakery Visual Composer” I got with the theme that I used for a while… it stopped working and now all I see in pages are coding (the plug in is installed and activated but no longer working)

What I did after this:

I disabled most of the plugins since the rest were working fine but I only disable the ones I added this week.

I uploaded a backup of the theme (noting that the theme is working perfectly and the website is working perfectly as well)

I tried to search for mistakes in coding of the theme but I couldn’t find any.

and I noticed that the problem is only in these pages:

– add new post
– add new page