If you forget a password to your merchant or affiliate login into Post Affiliate Pro, you can request new password. You will need to enter your email address (username) and write down the code written inside the captcha image.
However, if you do not see any captcha image, please check your PHP settings (/scripts/phpinfo.php) and GD support must be enabled.
Sometimes, FreeType library is required.
Please, read more here: https://php.net/manual/en/function.imagettftext.php
Or you can also switch to google captcha in Merchant panel > Configuration > Captcha