My mp3/4 player only plays a few seconds of each...

Question

When I upload music to my mp3/4 player it only plays a few seconds of each song. When I first bought it it had full songs on it. I then deleted them and tried to put new music on it. Now it is not working properly. There is no name brand on the player but, I bought it from overstock.com model CNMP4-2G.

Please Help!!!!