not enough free space in memory

I was listening to my MP3 Player 1 day & it stopped all of a sudden. I couldn't get it to play or even turn off. Now I plug it into laptop to charge & it charges and then says Not enough free space in memory. And something about deleting files. That screen disappears & when I try to play music it reads No songs available for playback. Please connect to compliant software or device and transfer songs. I tried to move more songs over and everything looked like the songs went but still can't get to any songs.