I have a backup of my finished games "save game" on the pc but sadly it was at the new game only so give a call to my best friend "Google" and you soon get
here and sure after that to
this.
Then play some minuted and you will get
there.
Well, if you are so stubborn, then download
this, it's a tool all on one.
Decompress it and start it.
File> open and choose your nds file of Hotel Dusk room.
Now press the NDS icon in the toolbar and you will get a new window with all the files you have in that rom.
In that new window go to File > split rom and then choose where to save; this will break down your rom into the files that they compose it.
The problem here is that if you take a look at those files, you have many file pair with the same name and the extention .tbl /wpf.
The tbl files are a list of files with the offset that you have inside the wpf file and this subfiles are compressed.
Now you would need to break down this wpf files into the single pieces and for that you can go 2 ways:
-is to program your own toll
-just use the hex editor because inside the wpf files you can see the names of the files at the top of each file.
In Crystal tile, you can view the tiles as in tile moloster, you can try that by pressing the icon with the painting and the grid on the tool bar.
On the left you can change the colors deeps that should be 1/2/4/8 bpp (i think your images are 4 or 8 bpp).
What else can i tell you?? Check the name of the files, normally they hint you what is inside (double click on the file data>local>us>itemtext.dat and look on the right side of the window with all the numbers to understand what i mean

)
I can't help you in how to crack the compression because I am not so good at that as well.
Maybe try to find the smallest image possible (by the name) and try with that one.
And the last help is
here.
Good luck