You have had many posts downvoted in a short span of time today. Assuming these votes were all cast by the same user, they will be reverted automatically. Since this is done by a nightly job, wait 24 hours. If the votes are still there after more than 24 hours, use the contact form and explain the issue (moderators don't know who voted for what, but some ...
I sympathize, and I understand how it can be demoralizing to put in a lot of effort into an answer only to never receive any reaction or feedback at all. It can feel like you are writing into a void, and that's not very motivating. I sympathize with the problem you've identified.
Let me suggest a different way to address the problem. Rather than trying ...
Some users ask a question and disappear. Maybe they found an answer elsewhere. Maybe they don't care anymore. Maybe they they lost the cookie to their account. There's nothing you can do about that.
Users with less than 15 reputation cannot vote.
Any user can accept an answer on a question they asked (except during the first 15 minutes). They are not under ...
Your math is incorrect.
Voted on 600 questions
You've only voted on 361 questions. You have not voted on 600 questions, so you don't qualify for the badge.
The two criteria are linked by and, so it isn't enough to satisfy one of them, you need to satisfy both.
Given the current state if the system, I think the answer is "nothing can be done".
As long as there are any votes, you can not know if the asker voted.
There is no way to force them to vote or accept.
All you can do is not to answer questions of users that you know to be "ungrateful".