So i started the companions guild and was asked to intimidate this guy in whiterun. But, before i did this i did one of the imperial legions "battle for whiterun," where in my adrenaline rush, might have killed this guy.. He now stands as a pile of ashes at the end of the pathway of dragons reach, right before you go down the stairs, with the quest icon above him.

Does anybody know how i would fix this? i would go back to an earlier save.. but that was about 100 hours ago.. So not worth it at all.

Well you're on the PS3, so you cannot resurrect through console nor would necromancy provide an ample cure to this problem.
The only thing I can think of is to fail this Companion Intimidation quest and get another, different one through the same NPC.

So attempt to attack one of The Companions untill they become hostile, then run away, pay the bounty and see if it failed.