An unanswered or unexplained issue or problem.

असमाधित

English Usage: The murder case remains an unsolved mystery.

Hindi Usage: हत्या का मामला एक असमाधित रहस्य बना हुआ है।

To leave as unanswered or without a solution.

समाधान न करना

English Usage: The detective was unable to unsolved the riddle.

Hindi Usage: जासूस पहेली को समाधान न कर सका।