How to rebuild system databases in SQL Server 2005

Rebuilding the master database installs all system databases to their initial location. Use below procedure to rebuild the master database for a corrupted installation of SQL Server also.

To rebuild the system databases you need to run the setup command from the Command prompt and follow the following procedure:

1. Click Start, click Run, type cmd, and then click OK.
2. Run the following command to rebuild the system databases:

start /wait \setup.exe /qn INSTANCENAME= REINSTALL=SQL_Engine REBUILDDATABASE=1 SAPWD=StrongPassword

For example:

start /wait D:\setup.exe /qn INSTANCENAME=MSSQLSERVER REINSTALL=SQL_Engine REBUILDDATABASE=1 SAPWD=password

The /qn switch Writes all Setup messages, including error messages in Setup log files. The log is located at %ProgramFiles%\Microsoft SQL Server\90\Setup Bootstrap\LOG\Summary.txt

The /qb switch can be used instead of the /qn switch. /qb allows the display basic setup dialog boxes and all error messages.

SAPWD is needed to specify a new password for the System Administrator account. Microsoft recommends de use of a strong password.

The parameter INSTANCENAME is used to specify the instance name. Use MSSQLSERVER for the deafult instance.

Ref: http://msdn2.microsoft.com/en-us/library/ms144259.aspx