MAJOR SPOILER...

Whiterun-
Okay so a while back ago Stormcloaks took Whiterun. I was thane when they took over and had the Breezehome. I upgraded the house once. Now I am much further into the game and I cannot find the steward to upgrade my house. The old Jarl is gone and Vigor(?) is now in-charge. The steward is gone. But I have heard, a girl is the steward. I found a girl near the Jarl near his throne. But she does not have any diolouge with me. So she just says things like "what do you want?" I was wondering who do I go to to upgrade my house then..

Ulfric Town(?)- I forget what town Ulfric Stormcloak owns but, I cannot find his steward either. I bought the house from one of his men and the man does not let me upgrade my house so where do I go for that too?

Additional details: Xbox360. Level 36. Thane in both of the towns.

the girl is not the steward, its a guy. i usually find him sitting in the room behind the throne room. (go up the stairs to the right of the throne). His name is Brill. He always seems to be eating...

Okay so I have not found the steward. I did find Brill though, dead in the middle of Whiterun.

You may be able to use the old Steward who is in the basemant of the pallace in Solitude with the old Jarl

If he's dead then you are probably out of luck.

Even if Stormcloaks took Solitude?

Vignar is odd in that his court (Housecarl and steward) are not essential. Brill is dead, and Proventus is exiled. I'm afraid that you're out of luck.

I highly doubt that Proventus will give you the time of day, seeing as you helped kick him out of a lucrative job. And anyway, he has no more authority in Whiterun. But do visit the folks in the Blue Palace basemant. They'll have some choice comments to make.

Edit: Jorlief is still steward in Windhelm, regardless of the war's outcome. Is he dead too?

He is alive. I had to do the murder quests before upgrading my house.