How do i find a mars dungeon key please reply

I went to Ismeralda to do the riddle mission and it gave me a mars key so i went to the mars dungeon and i got killed and lost the key so i was wondring if i could get another key or find one to complete the mession that i started and died half way through .

i have help a player yesterday and he finished her quest if you get killed simple delete that part of the mision and talk to npc again you will restart that part of the mision and you will get a new key