Here is how to recover the embedded DB password on the VMware vCenter Virtual Appliance (VCVA):
From the console (or SSH) of the VCVA run this command:
grep EMB_DB_PASSWORD /etc/vmware-vpx/embedded\_db.cfg
From: http://kb.vmware.com/selfservice/microsites/search.do?language=en _US&cmd=displayKC&externalId=2004506