Abandoned, unanswered questions can be a nuisance for readers when they appear in search results. While every question deserves a chance to be answered, at some point the annoyance to those searching for a solution outweighs the increasingly-small chance that an answer will be provided.
For this reason, the Community user will automatically delete old abandoned/dead questions in the following circumstances:
If the question is more than 30 days old, and ...
- has −1 or lower score
- has no answers
- is not locked
- has no active bounty
... or ...
- it was closed and migrated to a different site
...or...
- it was migrated from a different site, and then rejected
... it will be automatically deleted. (These are termed "dead" questions in the code.)
If the question is more than 365 days old, and ...
- has a score of 0 or less, or a score of 1 and a deleted owner
- has no answers
- has no active bounty
- is not locked
- has view count <= the age of the question in days times 1.5
- has 1 or 0 comments
- isn't on a meta site
... it will be automatically deleted. (These are termed "abandoned" questions in the code.)
These checks are run every week across all sites.
If the question was closed more than 9 days ago, and ...
- not closed as a duplicate
- has a score of 0 or less
- is not locked
- has no answers with a score > 0
- has no accepted answer
- has no pending reopen votes
- has not been edited in the past 9 days
... it will be automatically deleted. (These are termed "abandoned closed" in the code.)
This check is run every day across all sites.
If you believe your question can still be answered (by you or anyone else), see this Q&A on Meta Stack Exchange: What should I do if I find the answer to an old question of mine that was automatically deleted as abandoned?
See also: The official "How does deleting work? What can cause a post to be deleted, and what does that actually mean?" FAQ meta post.