Problemas para conectarme a mi SQL SErver 2005

Question

Tengo instalado el SQL Server 2005, generalmetne me conecto a un servidor externo y no a mi local....pero ahora que necesito trabajar localmete no puedo conectarme me sale el sgte mensaje.

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible.
Verifify that the instance name is correct and that SQL SErver is configured to allow remote connections.
(provider:TCP Provider, error:0-no connection could be made because the target machine actively
refused it)(Microsoft SQL Server, Error:10061)

trate de ingresar al SAC pero no puedo me muestra el sgte error:

No SQL Server 2005 components were found on the specified computer. Either no components
are installed, or you not an administrator on this computer. (SQLSAC)

POR FAVOR AYUDENME A RESOLVER ESTE PROBLEMA!!!!

Muchas Gracias.