Recently I decided to change my blog theme to a single colomn style, I had completed all the step up to the theme selection in the wp control panel, and now come to the customization of the header link to my contact and portfolio, I follow one of the theme designer guide to write a (contact) 'page' instead of a post in my wp control panel, once I decided to publish the page, the problem start from here, it says error connect to the data base. from here my whole blog was down with no access to the wp control panel, no access to any user.
so I decided to delete the contact "post" from my data base . and delete the .htaccess file from my server control panel, and ftp the .htaccess file again into the blog main directory again, with this step. everything was back to normal again.
hope this idea may help the people who have this problem in some way.
cheers
Alex