All WordPress blogs by default have comments open on all Pages and Posts.
Those comments are found here in the dashboard >
and when approved the automatically appear in the comment stream on the post or page they were submitted to.
I suggest you restore your blog to default ie. normal.
You can enable and disable comments on free hosted WordPress.com blogs on this page > Settings > Discussion
Discussion settings is where you set up defaults for comments.
You can override the default settings and enable or disable future comments on any individual post or page.
Any existing posts or pages will need to have comments disabled manually via editing. You can use the bulk edit feature in the all posts and all pages screen to make that quicker.
Note: By default, new blogs on WordPress.com will have the Discussion hidden. You can reveal it by clicking on Screen Options http://en.support.wordpress.com/screen-options/ on the top right corner of your Admin page, and checking the box that says Discussion so the module is included. http://en.support.wordpress.com/modules/#list-of-modules