How to start a named instance of SQL Server in single-user mode (Command Prompt)

SQL Server Setup Help

To start a named instance of SQL Server in single-user mode from a command prompt

From a command prompt, enter:
sqlservr.exe -c - m -s {instancename}

Note You must switch to the appropriate directory (for the instance of Microsoft® SQL Server™ 2000 you want to start) in the command window before starting sqlservr.exe.