If you are running wordpress and wondering why the images are not resizing the problem is probably that you don’t have gd extension installed or enabled in your php configuraiton.You can check thru your terminal is the gd extension installed with command:
Or to open call phpinfo and check for gd library.
If you don’t find GD library, please install it and you are done.
p.s. Be sure you reupload the images again.