Q&A for How to Escape the Thalmor Embassy in Skyrim

Take a LOT of invisibility potions, about 50. Use them every time you are spotted. They should chase you around but not be able to find you as long as you have a decent sneak skill and move fast. Some healing potions are also a good idea. There is no way to go through the dungeons without killing the torturer and at least one, maybe three, guards as one of them has the key to the trapdoor which can't be opened without it.

There is no way to do the whole mission without alerting or killing anyone.

Flame Antioch saved my bacon; I threw one down before going into combat. Also, pick them off one at a time as much as possible. I also upgraded my gear when I looted; the gear chest didn't have anything in it, so I started with a stolen ax from the kitchen and upgraded as I went.

The only way to start over is to load an earlier save. Unfortunately, you can't start over any other way than that.

Use fire spells or staves as all trolls are susceptible to fire in Skyrim (see herbane's beastiary) or just run past the troll.