If you’ve lost access to the Facebook account you use to log into Feeld, you can’t use it to log in to Feeld anymore.
If your Feeld account also has an login method active, you can still log in to Feeld that way.
If you don’t have another login method associated with your Feeld account, contact Feeld Support. They can help you regain access to your account after verifying your identity. Be sure to include the email address that was associated with the Facebook account you lost access to when you reach out.