I have done a website which is located in the sub-directory (eg: www.domain.com/website)

The root directory  www.domain.com), is showing this IIS7 page.

I have login on the website which is at the sub-directory (www.domain.com/website) and changed to redirect this website (www.domain.com/website) to re-direct to the root directory (www.domain.com) which is showing this IIS7 page

I realized the mistake that I have made and unable to login to remove this redirection from (www.domain.com/website) to (www.domain.com)

On clicking the login link, the message it shows as seen on this screenshot: http://netservo.com/dnnimages/001.jpg

 
I have looked in the forum and find a number of similar issues posted and I followed the instructions to edit the database file. However after installing SQL Server 2008 Management Studio Express I am unable to open the databse.mdf file to edit the redirect link

I am new to DNN and I am not sure what I am suppose to do the fix this issue or if  I have misinterpreted the help instructions from the other post.

I hope someone here can guide me to fix this problem but giving me some steps on what needs to be done.