Recreate EM DBCONSOLE :

Remove the following directories from your filesystem:
/
/oc4j/j2ee/OC4J_DBConsole__

If the dbcontrol is upgraded from lower version, for example, from
10.2.0.3 to 10.2.0.4, then the following directory also needs to be removed from the file system.
/.upgrade
/oc4j/j2ee/OC4J_DBConsole__.upgrade

NOTE:
On Windows you also need to delete the DB Console service:
- run regedit
- navigate to HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services
- locate the OracleDBConsole entry and delete it

Alternatively on Windows XP and Windows Server 2003 you can run the following from the command line:
'sc delete '
- where is the DB Control service name (typically: OracleDBConsole)

OR use the command,

'nmesrvops delete '
- where is the DB Control service name (typically: OracleDBConsole)

Also available from Microsoft is the delsrv.exe command. (Free download from Microsoft)



Step 1: Drop AQ related objects in the SYSMAN schema
Logon SQLPLUS as user SYS
SQL> exec DBMS_AQADM.DROP_QUEUE_TABLE(queue_table=>'SYSMAN.MGMT_NOTIFY_QTABLE',force=>TRUE);

Step 2: Drop the DB Control Repository Objects

Logon SQLPLUS as user SYS or SYSTEM, and drop the sysman account and management objects:
SQL> SHUTDOWN IMMEDIATE;
SQL> STARTUP RESTRICT;
SQL> EXEC sysman.emd_maintenance.remove_em_dbms_jobs;
SQL> EXEC sysman.setEMUserContext('',5);
SQL> REVOKE dba FROM sysman;
SQL> DECLARE
CURSOR c1 IS
SELECT owner, synonym_name name
FROM dba_synonyms
WHERE table_owner = 'SYSMAN';
BEGIN
FOR r1 IN c1 LOOP
IF r1.owner = 'PUBLIC' THEN
EXECUTE IMMEDIATE 'DROP PUBLIC SYNONYM '||r1.name;
ELSE
EXECUTE IMMEDIATE 'DROP SYNONYM '||r1.owner||'.'||r1.name;
END IF;
END LOOP;
END;
/

SQL> DROP USER mgmt_view CASCADE;
SQL> DROP ROLE mgmt_user;
SQL> DROP USER sysman CASCADE;
SQL> ALTER SYSTEM DISABLE RESTRICTED SESSION;


to create the dbconsole you need to:

ORACLE_HOME/bin/emca -config dbcontrol db -repos create