Is there a "bump" feature to move an old unsolved/unanswered question to the top of the list?
Editing your question bumps it to the top in the "Active" list (default for all visitors).
But just don't edit it to bump it, add more information, the results of your research, etc. so that it has a better chance of being answered. If you're not getting any answers at all you usually need to add more information.
You can also add a bounty: