If this happens you have to login to your database manager and execute this query

UPDATE `lh_chat_config` SET `value` = 'a:4:{i:0;b:0;s:8:"site_key";s:0:"";s:10:"secret_key";s:0:"";s:7:"enabled";i:0;}' WHERE `identifier` = 'recaptcha_data'

If you still cannot login disable cache https://livehelperchat.com/how-to-enable-cache-71a.html