The repositories seem to be down at the moment, they should be back by tomorrow I guess.
Use the mirror to download applications.
# Extras
deb http://espejo.freemoe.org/repository.maemo.org/extras/ fremantle free
Or just click this in the N900 browser http://freeeee.org/espejo-maemo-extras.install

Edit: As for the music problem can you be more specific on how it is not recognized?