different result and index

site:www.mywebsite.com and without www

[digic]

Last month my site index well with google until last week it disappears and only the home page was left when I type the site:www.mywebsite.com. But when I type the site:mywebsite.com (without www), it shows me more indexed pages.

How does it happen and what are the things I should do?

[caveman]

Try this thread on www versus non-www [webmasterworld.com]. ;-)