Starting SQL Server Agent
SQL Server Agent runs as the SQL Server Agent (MSSQLSERVER) service, a Windows service that executes jobs, monitors SQL Server, and fires alerts. SQL Server Agent (MSSQLSERVER) is the service that allows you to automate some administrative tasks. As such, you must start the SQL Server Agent (MSSQLSERVER) service before your local or multiserver administrative tasks can run automatically. SQL Server Agent runs as a service called SQL Server Agent (MSSQLSERVER), if it is the default instance, or SQLAgent$<instancename>, if it is a named instance.
If the SQL Server service and SQL Server Agent service are not configured to start automatically, you must start them manually.
See Also
Tasks
How to: Start SQL Server Agent (SQL Server Configuration Manager)
How to: Start SQL Server Agent (net Commands)