The first one is incorrect (as my English could very well be).
The second one could be meant as a joke (how surprising? nobody has voted for you? meaning you are a jerk).
The fourth one sounds like a proper question, without any second thoughts.

Here’s how I’d translate these :

How did nobody vote for you ?!

What do you mean, nobody voted for you ?!

How come nobody voted for you ?!

(same as above)

The last two mean the same thing, the second is just more formal than the first one. The inversion (se fait-il instead of ça(il) se fait) often makes a phrase more formal.

"Comment ça" means you don’t understand how it happened or you don’t believe it, you’re asking the other person to explain.

I would not use the first one, but in many other cases it’s correct. It implies the person knows how it happened exactly. If you fell off you bicycle, one could say "Comment t’es tombé ?! (en vélo)", then the other person would explain how it happened, etc. In this case, you can’t really know why nobody voted for you so I would use that.