It was deleted by the system after being identified as "abandoned", see the official post about it here:
Just to formally document the exact policies we have in place to remove old abandoned / dead questions:
If the question is more than 30
days old, and ...
- has -1 or lower score
- has no answers
- is not locked
... it will be automatically deleted.
Your question was posted over two months ago, has -1 score and no answers and it's not locked - thus got deleted by the system scheduled task.
Edit: this same process also delete zero scored questions:
If the question is more than 365 days old, and ...
- has a score of 0 or a score of 1 with a deleted owner
- has no answers
- is not locked
- has a viewcount <= the age of the question in days times 1.5
- has 1 or 0 comments
... it will be automatically deleted.
This check is run every week across all sites.