I can't complete the quest cause there is no stormclaw soldier there to talk too . I red that if i hit the Mothral Jarl till he bends the knee the quest will auto complete. if it bugs but nothing happend ... What should i do ?
If all Imperials in the fort are dead, then the quest should have automatically completed. You'll just have to reload a save if everything isn't working; if that doesn't work, try fast traveling away and then back, or waiting for a while.