Bitcointalk per se doesn't have any tech supports or working email for such issues. Instead, we have the Meta section to discuss forum-related issues concerning functionality, technicalities, bugs, glitches etc. I have encountered that same problem you're having just a day ago and I suggest you bookmark this link in order to bypass captcha logins the next time around:

https://bitcointalk.org/captcha_code.php

Note: you have to be logged in on your account first in order to get your one-time unique code for bypassing captcha logins in the future.

Link to the original thread discussing captcha login bypass (made by theymos, the admin himself): https://bitcointalk.org/index.php?topic=5042674.0