Unanswered (adjective)

Not having been responded to; not having been answered.

Origin:

Late 16th century: from un- (expressing negation) + answered.

Examples:

1. The question remained unanswered.
2. His letter went unanswered.
3. Many complaints went unanswered.
4. Her plea for help went unanswered.
5. The mystery remains unanswered.