Comments temporarily unsubmittable

The ‘verification code’ (Captcha) feature at the bottom of the Comments-submitting form is not working. I don’t know why but have contacted my tech adviser who is many time zones away from me.
Please therefore don’t bother submitting comments until further notice (or, until you see the Captcha codes appearing at the bottom of the comment-submission form.)
Sorry about this.
In case the tech adviser is unavailable, if any readers can give me clear instructions how to fix my Captcha or install a new one without too much trouble, please tell me. My version of MT is 3.21. Thanks!