Probably the path has broken.
What sound format are you using? If the music is in wav format, you can embed
the music into the presentation. If you are using other format, you can also
try to convert the music into wav format using sound convertor. By doing so,
the music will be embedded into the presentation (preventing the link from
breaking).
Alternately for non-wav format,
Create a new folder and move the ppt and music into the folder.
Now, open the ppt file, delete and reinsert the music to create a pathless
link.
Then, save your presentation.
Move the folder to your jump drive.
Read about how to embed your music into the presentation, where to download
sound convertors and other related information here:
http://www.rdpslides.com/pptfaq/FAQ00155.htm
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