Thumbnails not showing

I recently have been trying to optimize my site, I tried 3 plugins, smush wp, BJ lazy load, and wp optimize.

It worked fine until suddenly the widget that shows image banner, it just shows the path for the file instead of the image, additionally, I can’t regenerate thumbnails because it shows the invalid path for file. All other images show fine on the website.

(Go to main page see the 3 gray boxes where 3 images are supposed to show.)

The page I need help with: [log in to see the link]