How to show comments section to all of my blog posts?

I have a little problem in my blog which is created with Wordpress.
When I creates a new post on my blog there's a option to post comment for my readers.!
But when my post get older than 2 weeks and the comments section hide?
Why?
for example look at this one.
There is an option to post comments on this post because it's fresh post.
http://guideandnews.com/2012/01/01/how-to-create-a-logo-header-image-for-your-blog/
And this one there's not any option to post comment?
http://guideandnews.com/2011/11/25/yahoo-site-explorer-shutting-down/
Please help me.
How to show comments option to all posts?

 

You missed a link there...By the way, your blog looks horrible in Safari...look --->

https://img.skitch.com/20120105-d6a6kh5i51yh5faww4mjksy7eh.jpg

 

Sorry, Now I put a link there, check it out now and help me please.

Thanks

 

But it's looking fine in firefox! Why it's happening ?

 

Go to the admin panel and check your post settings...there's a section under the post area looks like this...

 

I've already checked allow comments to all of my posts. It is showing in newer posts but it's not showing on those posts which is older than 2 weeks

 

Okay go your settings --> discussion, uncheck the box as the following screenshot suggests:

 

Wow wow:O YOu solved my biggest problem in my blogging career. I promise I'm not lying I have changed my blogs theme 2 times just because of this problem.

I never seen my discussion page in wordpress admin panel. Thanks GOD that my problem solved!!

Thank you very much Richie_Ni. You are genius!!!!