Keeps displying "bad track"

I'm sorry I should've been more clear. Every song that I put on there worked on it before. I never had any problem with any song on the mp3 before until recently. That's what I don't understand. It's like all the sudden it's deciding it just doesn't wanna play a LOT of songs. For example I put a lot of music on my playlist to listen to at the gym but it seems as each day goes by less and less work and that's the problem with the whole thing... all my music is doing that. And I know it's not an outside source like I said before cause I have only had to plug it up just once to charge it but this problem has been before that. Any other suggestions or helpline numbers??? I'm sorry I should've been more clear. Every song that I put on there worked on it before. I never had any problem with any song on the mp3 before until recently. That's what I don't understand. It's like all the sudden it's deciding it just doesn't wanna play a LOT of songs. For example I put a lot of music on my playlist to listen to at the gym but it seems as each day goes by less and less work and that's the problem with the whole thing... all my music is doing that. And I know it's not an outside source like I said before cause I have only had to plug it up just once to charge it but this problem has been before that. Any other suggestions or helpline numbers???