I don’t remember the exact details, but I think there was a way to either disable ldap and login locally, or have both types of log in possible. Something like enabling these:
and disabling one or two of the ldap login settings. I’m not recommending you mess with this on production just in case, but if you have a staging server see if changing those makes it possible to resolve the first login.
Otherwise is there anyone with an LDAP account who has left the platform? For our server I ended up anonymising someone who had left. It basically decouples the account from email and login, but keeps the account there so I can give it a variety of permissions and impersonate it(after giving it an appropriate name). Likewise I gave it some API keys and use it to perform automated tasks.