Step 1 : If your theme don't have attachment.php page copy single.php and paste it in same theme folder
Step 2: Locate and delete <?php the_content(); ?>
Step 3 : Add this code
<a href="<?php echo $post->guid; ?>"><img src="<?php echo $post->guid; ?>" alt="<?php the_title(); ?>" /></a>
Now your attachment page will display full size image with a link to oriinal file.
Step 2: Locate and delete <?php the_content(); ?>
Step 3 : Add this code
<a href="<?php echo $post->guid; ?>"><img src="<?php echo $post->guid; ?>" alt="<?php the_title(); ?>" /></a>
Now your attachment page will display full size image with a link to oriinal file.