TH2014 RCA MP3 not charging?

So my sisters MP3 Player is not charging, it is a TH2014 RCA MP3 Player, I can plug it into the PC and put songs on, but when I unplug it, it will not turn on, and when it is plugged in the screen has a pic of a PC, little Z's, a folder and a pic of a battery, but the battery is not charging