As long as you (or your colleagues) don't have any serious test data you've been working on that needs recovering, it's pretty simple to generate a fresh instance! 
First, search for the SQL Server script that builds the demo database under \Mssql\Install. The name of the script is called: instnwnd.sql . If the script isn't found there, an alternative place to look is under the Visual Studio SDK path(s), for example: C:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\Samples\Setup . If the script is still missing in action, try searching for the file. Once you have located the file, open a command window and navigate to that directory path. Once there, type:
osql -Usa -Psapassword -SMyComputerName\MyDBServerName -iinstnwnd.sql -oinstnwnd.log
(READ: -U = username, -P = password, -S = DB Server Name -i = input script -o = output log.)
To be sure that the script executed correctly, open the instnwnd.log file and review the results.
That's it!