You can "elevate" an unanswered question by helping to improve it.
- Make sure it has the right tags, so it shows up to subscribers of those tags.
- Make sure it has the right keywords and phrases so it shows up in searches.
- If output or additional detail or troubleshooting tests have been requested but not provided, help provide it. "I have the exact same issue, and my output is...."
- If the question is clear but poorly written, offer a suggested edit (rewrite) for the community to review.
After you edit an unanswered question, it pops to the top of the Home page and gets immediate visibility by a lot of the volunteers here. It will, of course, slowly start working its way downhill as other edits and posts grab that coveted top position.
DON'T hijack a question into something different with your edits. Make sure you are really improving the original question, and helping to make it answerable.
DON'T make trivial changes to a Question just to keep recycling it to the top. Trying to game the system will quickly attract the ire of a Moderator.
DON'T make changes to an answered question if the answer didn't work for you. That often means your problem is different. Instead, post a new question clearly showing how it didn't work -- and is therefore not a duplicate.
Also, many questions are unanswered simply because they are unanswerable as currently written. Maybe they lack detail. Maybe they have a conceptual flaw. Maybe the person asking was misdirected. Questions that are obviously off-topic or abandoned with insufficient data should be closed instead of elevated.
Finally, the answer you need might be in AskUbuntu already...but attached to a question that is differently worded, misspelled, or have the wrong tags. A few minutes trying to outwit the Search box with different terms and permutations might payoff handsomely. If you strike gold and find a great answer to a poorly-written question, please help improve that question so others can find it without suffering.
P.S. ...and, of course, remember to post an answer to your own question if you discover a better answer on your own!