BTW:
Helping with 3D modelling without a model is like washing feet in socks.
Share your model, maybe someone can help you more.
Thank you. It is good method within one group. Not for the whole house plus furnitures. It seems there is no one click way to solve this even if ruin it just by one click.
No. There is no way in the free web version to fix your error in one click.
You just couldn’t have “ruined” your entire house with one click because the ‘Unhide All’ operation is affecting only the current context. You are contradicting yourself now that you change the discussion to groups and their own contexts.
Added: (keep reading next post by @dezmo!)
According to @dezmo’s post ‘Unhide’ digs through lower (nested) groups and components to unhide. I’ll have to investigate this changed, unexpected, unwanted ruiening behaviour. It’s like ‘Delete Guides’ that does not give you the choice between ‘contextual’ or ‘overall’ and deletes all guides, often undecired!
Well, you - and every normal user, including me - rightly assume so, because it was like this since the beginning of time.
However,I just realised that - due to a thoughtless and completely incomprehensible decision, this is no longer the case. There is nothing about in in a changelog either, but:
In the web version “Unhide All” command un-hides all hidden geometries and objects including nested.
This is unusual, unexpected behaviour, and I don’t see a reasonable explanation for the unannounced change.
So yes, the topic starter screwed up her previous work with one click.
I personally regret this very much. I hope the developers reconsider their decision.
__
And I apologize for not understanding the problem and not looking into it more closely earlier. However, the suggestions I made in my #9 comments still stand. 
Wow, I didn’t expect any Sage would try to understand and test before he gave any conclusion. And even I really want to explain everything but I will never make so ■■■■ good and clear!
My work was saved by the dumb way I mentioned above and lesson learned. Thanks for your sympathy and everyone was once beginner. But we will grow because there are someone like you to really listen and help us!
I hope the developers can see what you said and make some changes unless they made this pain on purpose for obvious reason. But to some people just for hobby, the web free version is already enough and takes lots of time to learn and master. The pro versions will be definitely overwhelming plus most of the functions maybe I will never touch.
All in all, I love SketchUp. It is the most awesome app I have ever used! (I have tried few before this)
I guess this is the end of this topic. Big thanks to your explanation! And I am appreciate your professionalism!
Cheers 
I couldn’t have known there were differences between one and another Free Web application from the same date. Weird!
Using the latest online SketchUp Web Free (January 9) ‘Unhide All’ is still context sensitive meaning that it only unhides All that was hidden in the current drawing context. As I wrote in post #24 above. Yours seems to have worked incorrectly, not as desired, unexpected and not according to how it has always worked, more like with @dezmo and some others.
So yes, I was trown off by you mensioning groups.
My test was three cubes:
- first one was ungrouped with some edges hidden, some smooth and/or softened.
- second one grouped, also with some edges hidden, some smooth and/or softened.
- third one grouped and as a group nested in the second one. Third one also with some edges hidden, some smooth and/or softened.
Now in top level I selected all and applied ‘Unhide All’. Only the raw hidden edges became unhidden. Hence my answer#24
From your experience you were completely correct though!
Thanks for your time to test. I apologize if my explanation was confusing. As a non English speaker and beginner to SketchUp, I have lots of room to improve my skills literally!
No need to at all. It was clear though I couldn’t know with my up to date version and you were right to bring this to attention.