$ oerr ora 12514
12514, 00000, "TNS:listener does not currently know of service requested in connect descriptor"
// *Cause:  The listener received a request to establish a connection to a
// database or other service. The connect descriptor received by the listener
// specified a service name for a service (usually a database service)
// that either has not yet dynamically registered with the listener or has
// not been statically configured for the listener.  This may be a temporary
// condition such as after the listener has started, but before the database
// instance has registered with the listener.
// *Action:
//  - Wait a moment and try to connect a second time.
//  - Check which services are currently known by the listener by executing:
//    lsnrctl services <listener name>
//  - Check that the SERVICE_NAME parameter in the connect descriptor of the
//    net service name used specifies a service known by the listener.
//  - If an easy connect naming connect identifier was used, check that
//    the service name specified is a service known by the listener.
//  - Check for an event in the listener.log file.

SQL> ALTER SYSTEM REGISTER;

System altered.

//listener.ora should be something like this
//manually add the first SID_DESC according to your settings

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = <name>)
      (ORACLE_HOME = <OH>)
      (GLOBAL_DBNAME = <name.domain>)
    )
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = C:\oracle\product\10.2.0\db_1)
      (PROGRAM = extproc)
    )
  )

# tnsnames.ora Network Configuration File: C:\oracle\product\10.2.0\db_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

name =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = name)
    )
  )

EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

//it should work fine now but you have to manually restart the 
//database instance
//BTW lsnrctl stop and start the listener first before editing conf 
//files.