I am not sure, how you locked everybody out.
Which ldap credentials did you enter incorrectly? The credentials of the service user for ldap? Otherwise I can't explain that behavior. Could you not reset the password/user in ldap?
Or did you configure a password policy in LDAP and/or in Liferay?
Is there an exception in the logfile? Maybe you hit a different problem.
On top of that, you should also still be able to authenticate with the Omniadmin. It is usually the initially created admin user.
---
To your second question: There is a checkbox "LDAP required". If you uncheck it, it allows you to authenticate with the Liferay password. Please note that this will probably force you to have two passwords. One in Liferay, one in LDAP. I would try to avoid that. Believe me, it is usually less of a hassle to cluster ldap servers and make them highly available. (I work for several companies where ldap is simply never down, since all hell would break lose if that happend)
