Here are your options, in somewhat of a preferred sequence:
Make a regular comment on the question, stating why you want to re-open the question. This could include a brief description of your solution, or just stating why the question isn't a duplicate. Don't just state that you want to answer it, because the reason for duplicate closure in the first place ...
The question has been reopened.
Btw. there are many comments on the question, perhaps some are obsolete today and could be cleaned? If yes and if you would flag those you cannot remove yourself, we can help cleaning.