Your database instance is running. You are not able to access Oracle Enterprise Manager Database Control because the listener is not started.
Which tool or utility would you use to start the listener?
A.
Oracle Net Manager
B.
Listener Control utility
C.
Database Configuration Assistant
D.
Oracle Net Configuration Assistant
Explanation:
http://download.oracle.com/docs/cd/A97630_01/network.920/a96581/lsnrctl.htm
Listener Control Utility:
The Listener Control utility enables you to configure listeners to receive client connections. You can access the utility through Enterprise Manager or as a standalone command-line application.