I Installed MS SQL 2008 R2 Express And Plesk 11 MS SQL Hostname is ".\MSSQLSERVER2008" Right Now !
I Want Change it to "localhost"
Can U Help Me ?
It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, see the FAQ.
That's not the host name, it's the instance name.
So to explain further, what you've got there is a connection string with the following format
For more information on instance names, take a look at this question and answer. If you still want to change the instance name, as far as I know there is no reliable method of doing so without re-installing and picking the right name during the installation process, as discussed in this question and answer on our sister site for database admins.