Post Image Size Changed

I recently switched to “The Funk Theme” and a problem occurred. Now i am not able to get custom image sizes in posts. The custom size of all the images inside the post has been reverted and the default image size is taken (the image size in which the image was uploaded).
here is the link of my site http://www.internetwarz.com. You can see the problem which i talking about.
Can anyone please help me sort out this problem.