@Werner has already addressed the main subject of your query -- what the procedure may be for undeleting an "answer" -- so this posting will explain my reasons for having voted to delete the posting in the first place.

Basically, if we needed an "Exhibit A" for an opinion-based answer that's not in the least tinged by an effort to really address the subject at hand, the posting http://tex.stackexchange.com/a/222545/4686 certainly qualifies. Do we need such postings? I would argue that we don't.

In the first paragraph, an unsubstantiated opinion is offered as to what prompted Leslie Lamport to develop LaTeX (viz, to "provide a lift for newbies"). In the second paragraph, the writer tells us that he/she "simply hate[s] LaTeX". Maybe unsurprisingly, he/she offers no reason as to why anyone else ought to care about that person's opinion. In the third paragraph, we are exhorted, somewhat patronizingly, to read, re-read, and re-re-read the TeXbook -- the reason for doing so, presumably, being that by mastering Plain-TeX (more) fully, one needn't rely on the inferior and troublesome LaTeX. 

I fail to see how such an "answer" either contributes meaningfully to addressing the concerns voiced by in the original query or tells us anything that's not just pure personal opinion that's of no apparent relevance to others. And that's why I voted to delete the answer.