was Hazrat Khidar a prophet? Was he a messenger? Is he still alive? Someone argued that he still did not die.

Khidhr was a saintly person at the time of Musa (Álayhis salaam). Allah Ta'
ala refers to their meeting in Surah Kahf. Ilyaas (Álayhis salaam) was a
Prophet of Allah. According to the Muhadditheen, Khidhr (Álayhis salaam) as
well as Ilyaas (Álayhis salaam) passed away. According to the Sufis, both
are still alive.

and Allah Ta'ala Knows Best

Mufti Ebrahim Desai