A question like THIS is not irrelevant no unwelcoming too. But when the Question-asker himself/herself solved the problem and such a condition can never happen to anybody. And if happen, he/she can solve the problem similarly. So the scope of such question is a bit narrower to some specific conditions.
So, whether by Commenting or by Answering the Question/Problem is resolved.
I think such a Question can be CLOSED forever.
But we don't want to prevent spreading knowledge. So I'd recommend to pose a notice there like:
CLOSED: THE QUESTION OR PROBLEM IS MARKED WITH NARROW SCOPE
The Question or Problem is specific to some incidental conditions and might not happen without such a condition again to anybody. So the question is closed for further answer.
But till, if you want to put an excellent Solution/Answer to the question, Propose an Answer to the Question. A moderator will review your answer and then can be published.
The language can be whatever the community decides. The Special Answer given by someone will now be in a Queue to the Administrators, Moderators, or with certain Reputation users. After their approval as a correct/more relevant answer the Answer will be published.