I assuming you are referring to: How to make glowing particles, with a solid glowing center. Well there is not much you can do to change the votes on that question now.
You could edit it to make it a bit clearer what you mean, specify that you are looking for the particle and material settings to make that particle effect.
Yet even then the people who originally DVed probably won't be back to your question to change their votes.
However you shouldn't get too bothered by the down votes. You lost 6 rep from the three DVs, but gained 5 from the one UV, and two more from accepting the answer. So net on that question you actually gained one rep (so far).
I personally don't know why that question got so many DVs. We have had many others that simply ask how to do X, and are well received. For example:
How can I make a wrought iron basket?
How to animate morphing a rectangular plane into a sphere
How did I make this soccer-ball/honeycomb shape?
How to make a jelly material?
So in the end, no there is no way to "really undo" the negative rep.