Check if the MP3 is a VBR (Variable Bit-rate) or a CBR (Constant Bitrate) encoded file. Open the file in a player such as Winamp and check the description. Some older portable music players do not have support for VBR MP3s, so you won’t be able to hear them. There is also the chance that you’ve had a run-in with Digital Rights Management (DRM). Music vendors program the MP3 with limitations in an attempt to curb piracy. One of these measures is preventing the use of such files on portable MP3 players. Unfortunately, if the MP3 is protected, there is little you can do to play it.