Hi there and welcome
Can you tell me what type of music files these are? eg: Mp3, Wav, WMA? And where did they originally come from?
when you connect the Kindle to the computer, open the file manager then open the Kindle or Fire folder that indicates the Kindle, then copy the music to the music folder (has to go to this folder).
then make sure to eject the Kindle(click on the Eject icon near the time on the bottom right)
Then open the music app on the Kindle and it should then see the music.
Let me know how you go please.
ok, can be an issue with the SD card, can you put a different SD card and then check if it then dissapears after doing the transfer
Let me know the results please.
I would advise then to borrow one to test this, else the next step is a reset of the Kindle if you do not wish to try a different SD card. Its not about testing out a theory, its eliminating the causes for this problem.
The reset will remove all data and return the Kindle to new, so backup any data you wish to keep first. Books you purchased you can download again as with Apps.
Then Swipe down from the top of the screen and tap Settings. Tap Device Options, and then tap Reset to FactoryDefaults. Tap Reset to confirm.
Then setup the Kindle and see if the music then remains.
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