If you are talking about the BPS Pro JTC CAPTCHA then do the steps below to be able to login to your website to fix the problem.
Use FTP or your web host control panel file manager, rename the /bulletproof-security/ plugin folder to /_bulletproof-security/, login to your site, rename the bulletproof-security plugin folder name back to its original name, go to JTC and correct your JTC settings.
Since fixing this type of problem is very quick and simple to do you don’t need to remember the captcha or save it offline.