Is there anything that can be done to bring a question back to the top when it has received no answers?
You should not be bumping the question back to the top of the homepage by editing unless you legitimately have more information to add to the question. If you don't have any answers after 2 days, you can open a bounty on the question (in which you give up some reputation between 50 and 500 as a reward to the answerer).
Questions are "bumped" to the top of the active list by edits and by answers.
The active list is intended to show active questions, not be a home for tumbleweed questions. There is a section specifically set aside for unanswered questions:
Editing a question solely to bump it, without substantially improving it is a form of abuse.
Chances are, if a question has received no answers it could use some substantial improvement.
Possible areas of improvement:
- Poorly worded
- Too vague
- Too specific
It's also possible that there simply isn't anyone with the knowledge capable of answering it yet. Perhaps you could edit it to encourage users who may not know the exact answer to offer alternatives/substitutions or "close enough" answers.
I forgot that the Community user also monitors and bumps old unanswered posts as well.