Will I lose all the music when I replace battery on iPod classic?

I have over 12,000 songs on my iPod classic and all of a sudden it stopped holding a charge. I can play the music when it's placed in the apple charger.....but when I try to put it on my computer, I get a message to wait, that it's charging. It doesn't matter how long I have it in my computer, it will not charge it.

I hope someone can answer my question about losing of the music when they change the battery. I can't back it up as it won't show up on iTunes.

Thank you for any help or advice you can offer