Media library and gallery showing page not found

I have had issues going into the media library when I access it through posts and then edit post. When I click on Media library on the pop up box it displays a page not found from my website in an iframe when it’s suppose to list my pictures I have uploaded.

When I go to Media library directly from the dashboard it works absolutely fine and I can see all my images.

I’m not sure if anyone has come across this problem but I’d appreciate if anyone can advice me as to what to do.