I managed to download WinScp application and connected pc-n900 in this way. Thank you for introducing me to this method.

And I can find the .sounds folder (although it is greyed out) and the songs are there. So what I have in mind is just to create a new folder and transfer all my songs there. What do you think?

@qhubekela & dr_frost_dk, I am also installing Ubuntu file in livesystem, do I have to do it as well? I can already transfer my files.

I had also try to remove the file using CMD prompt. but it shows that the file cannot be found.

I have also DISK CHECK my device using PC but had to cut it short cause it is taking too long.

Would anyone know how should I remove that usbs file? It's kinda bothering to know that it still exist in my device. And I am worried that it might affect other partitions/apps.

Thanks to everyone who extended their help!