How do I start these questsé

I`m level 23 and the priest is never in Markarth and I can`t even engage dialogue with Kesh at the shrineé

Is there another wayé Do I have to do something firsté

EDIT: My keyboard is replacing the question mark with those crazy E`s....sorry

For "the house of horrors": enter the house, go downstairs with that guy who tells you about the house, kill him (don't worry, he will attack you), talk with the daedra god and then go and find the priest (I found him in a cave, he was held prisoner). The reward is a nice mace that can absorb souls.
For "the only cure": i don't remember how i got the quest but when i arrived at the shrine i didn't have a problem talking to Kesh...