I am in the ruins to retrieve the horn for the main story line. I just got the shout that allows ethereal and am on the upper level past the fire trap. There is a room that a cave in has partial blocked the room. Inside is a chest and other items but I cannot for the life of me find a way in. I though perhaps being ethereal would let me pass through but that does not work. How do you get in this room?

Be a switch or a chain in a room somewhere, in a dark spot or hidden. Some of these treasures you can see through gaps can also have an entrance a fair bit away from where you actually see them.
If you switch to the local map you can sometimes get a clue as to where it may be.

There's a way in, you'll have to jump from pillar to pillar across the broken bridges. Use the whirlwind shout to get across the gaps.

Edit: don't fret if you can't find your way in. There's nothing much but random loot.

You have to acces it by using one of those higher paths, it's crumbled though and you have to use Whirlwind Sprint in order to pass the gap.

Right. If it's the place I think it is, I was stuck there as well on my first play-through and ignored it. My second play-through and I noticed the pillars leading to a ledge. So basically you have to jump them in order to get to the ledge and get into that small section with the chest. I believe there's also a soul gem or ruby visible as well with a skeleton reaching for it or near it - if this is the place you're referring too, that's how you get to it.

it took me a while to get to that chest too.

there were a few hidden things in that dungeon.

i missed the word wall a few times.