Oracle DBA: The database is down. Please specify the host credentials to access database restart and diagnostics tools

The database is down. Please specify the host credentials to access database restart and diagnostics tools.
Enterprise manager shows that database is down but in real it is not.

[oracle@grhldb01 trace]$ sqldba

SQL*Plus: Release 11.2.0.3.0 Production on Fri Sep 13 10:38:01 2013

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, Automatic Storage Management, OLAP, Data Mining
and Real Application Testing options

SQL> select name,open_mode from v$database;

NAME    OPEN_MODE
------------
TCHDB   READ WRITE

check the listener status.

[oracle@grhldb01 ~]$ lsnrctl status

LSNRCTL for Linux: Version 11.2.0.3.0 - Production on 26-AUG-2014 13:16:23

Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))

STATUS of the LISTENER

------------------------

Alias LISTENER

Version TNSLSNR for Linux: Version 11.2.0.3.0 - Production

Start Date 13-MAR-2014 12:53:12

Uptime 165 days 23 hr. 23 min. 10 sec

Trace Level off

Security ON: Local OS Authentication

SNMP ON

Listener Parameter File /orabin/grid11gR2/grid/network/admin/listener.ora

Listener Log File /orabin/grid11gR2/base/diag/tnslsnr/grhldb01/listener/alert/log.xml

Listening Endpoints Summary...

(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER)))

(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1521)))

(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=10.128.0.42)(PORT=1521)))

Services Summary...

Service "+ASM" has 1 instance(s).

Instance "+ASM1", status READY, has 1 handler(s) for this service...

Service "TCHDB" has 2 instance(s).

Instance "TCHDB1", status READY, has 2 handler(s) for this service...