NB: This is general advice, meant to address the question "What do I need to do in order to get my question reopened?" I have read the specific question mentioned in this topic, but I have not gone over it in detail, and have no intention of addressing that question specifically. What follows is advice which is meant to help any asker who finds their question closed.
Your question has been closed. Now what?
If your question was closed as a duplicate then, if the system is working, you have received a useful answer, and you are happy. If not, then follow the advice given below.
If your question was closed for some deficit of quality or appropriateness for Math SE (e.g. if it was closed because it "needs clarity or context", it is "opinion based", it "seeks persona advice", etc), then you will need to edit your question in order to bring it up to the quality standards of the site. Remember that the main goal of Math Stack Exchange is to produce a database of questions and high quality answers, hence your question should be of general interest, and should provide enough information to explain why it is of general interest. This context should be added to the question via editing.
In order to get an idea of what kind of context is required in order to get your question reopened:
Read (and follow the advice given in) the meta question How to ask a good question.
Read the comments under your question. Respond to questions and requests for clarification—engage with the commenters. Finally, edit your question to address the concerns raised by the commenters.
Use the chat system. The room Constructive Feedback is a good place to get, well... constructive feedback.
Again, engage with the commenters, the people in chat, and anyone else who is trying to help. Folk on Math Stack Exchange may often seem cold, but this is not personal—there are a large number of people who seem to regard this website as a homework completion service, and a lot of the regulars are pretty cynical and/or jaded. Demonstrate that you are open willing to put in effort, and that you aren't just trying to get others to do your work for you. Respond to comments. Take the advice given. And remember: it isn't personal.
Once you have edited your question in order to bring it up to the quality standards of the site
Wait. The first time that you edit your question after it is closed, it will be sent to the "Reopen" review queue, where users with sufficient reputation will be allowed to vote to reopen the question.
Post a reopen request in the current reopen requests thread (note that this link may not be the right link in the future; a new thread is started from time to time).
Request reopening in the CURED chatroom.