Help ,page doesnt load

Hello

I have a big problem...i know its not blackhat stuff,but i hope someone can help me.
My wordpress blogs sometimes doesnt load with 'www' only with h.t.t.p:.//
Sometimes non of them works the only way to reach the blog is a link..
What can be the problem...and how can i fix it?

Thank you guys in advance!

There is URL redirection problem. Go to your blog dashboard and then setting option. There is URL option place full URL of your blog: http://www.domainname dot come.

Go to your cpanel and change it in database. You can take help of your webhost for this.