What version of Premiere Elements are you using and on what computer operating system is it running?
Where is this audio located in the project - one of the numbered audio tracks, Soundtrack? Is video linked to this audio.
Or is the audio standalone clip?
Please explain "...the sound file will not work"....
a. you see the file with its wave form in the audio track but the video plays back with no sound
What are the properties of the source file that you import into the project originally...brand/model/settings of the
camera that recorded this video/audio would help?
Have you added an narration clips to the project using the program's Narration Tool? And, if so, is sound
missing from the video audio as well as the Soundtrack?
How are you replacing the problem audio - the Replace Footage feature or other?
Let us start here and then decide what next.