You can recover the config from the pfSense install image as long as the partition is not completely destroyed, it gives you option before you install:
https://docs.netgate.com/pfsense/en/latest/backup/restore-during-install.html#recover-config-xml-from-existing-installation

Worst case you can cat the recovered config to the console from there and copy it out into a file.

Steve

Open a ticket with the support, they can 100% help you out.
https://go.netgate.com

-Rico

I would reboot the pfSense and when it completed, then reboot/repowered your CenturyLink modem. You'll then obtain an IP address for WAN.

I have not been able to reproduce the problem here, but I can see how it might happen. I opened https://redmine.pfsense.org/issues/9582 to track it and committed a fix: https://github.com/pfsense/pfsense/commit/45f95753963e497b5ce14493f9cca05336d75c7b

You can install the System Patches package and then create an entry for 45f95753963e497b5ce14493f9cca05336d75c7b to apply the fix.

Alternately, you can use viconfig to edit the config and remove that <vlans></vlans> line, or download a backup, edit it out, then restore.