Have you lost administration control of your MSSQL 2008?
I lost control of my MSSQL 2008, unable to create new databases and change server settings… pretty annoying.
I think it happened because I upgraded from SQL Express 2005 to 2008.
Well if you have the same problems, then you can either uninstall and then install the SQL Server 2008 again… or you can do as me 
Before you start, make sure the current user is member of the administrators group.
- Shutdown the SQL server service, agent service, browser service etc.
- Open a Command prompt
- Navigate to the SQL 2008 installation directory. E.g.:
"C:\Program Files\Microsoft SQL Server\MSSQL10.SQLEXPRESS\MSSQL\Binn" - Run "sqlservr -m -sSQLEXPRESS" (SQLEXPRESS should be the name of your instance)
- The SQL server should now be started in "Single User admin mode".
- Open "SQL Server Management Studio", remember, if you use Vista, to run as administrator.
- Open your instance and change your user to sysadmin.
- Close "SQL Server Management Studio"
- Goto the command prompt and shut down the SQL server instance (press CTRL-C, I think)
- Start the SQL service again
You should now be able to create databases again.