If you used outside sound files as part of your show, then all the outside sound files have to exist, too, and in their original locations, names, and folders.
Audacity, unless you changed it, does not pull sound files into itself for editing. It leaves them wherever they happened to be living and refers to them at the right times. If you have the Audacity aup file and the _data folder without all the external sound files, then you have no show.
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http://kozco.com/tech/audacity/aup1.jpg>>>
Look down about line 7 on this illustration and you will see a directory and filename. If piano2.wav file is not in that exact correct folder, my show turns to dust.
You can put all the sound files back where they were and the show will magically leap to life.
There is a more official write-up on this, but I can't find it. It's buried in the additional information at the top of this page.
There is a serious effort on the part of the Audacity people to change this behavior because it burns so many people. There is a setting inside Audacity Preferences to copy all audio inside itself during editing. This can make the show files enormous, so there is pushback on changing it.
Koz