As the first post tells you, you should "Run Nagios from the command line with the -v option to verify your config before restarting. (PID=22792)"
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
It will probably tell you where your errors are.
Also, from the line:
"Lockfile '/usr/local/nagios/var/nagios.lock' looks like its already held by another instance of Nagios (PID 33019). Bailing out..."
it could mean that nagios is already running.
So, try to stop nagios with ./nagios stop
and check that nagios is stopped with a ps -ef | grep nagios, and kill any process remaining (just to make sure).
then, try starting it again
Hope this help