Mp3 player. please,i, after copying musics,pictures,and some documents that's a(a publisher

Question

please,i, after copying musics,pictures,and some documents that's a(a publisher document).it then was giving me a number of errors:1)as the mp3 normally works using a battery i switch it on,then press play indicat's that there're no files,meanwhile when i connect it to any computer and try to open the contents there're a files inside?