It sounds like you may have gone through the “Align head-mounted camera” process which is meant for cameras that are literally mounted to the head. Once done, as I understand, this can’t be undone in the current version.
See if you can revert to an older version of your prefs in File->Load Prefs Backup. If you cannot, you’ll need to either manually remove the components of the prefs file related to Head-mounted camera or simply delete the prefs file entirely and start over.