Did you use Windows Media Player to rip the songs from CD? If you didn’t change the settings, it will rip to protected WMA. You should change the settings to have it rip to mp3, and choose at least 192 for the bitrate for decent sound quality(I use 256 kbps). If your songs were ripped to protected wma, I suggest you rerip them to mp3 and use at least 192 kbps.
Are these mp3 files, or in another format the player supports? If they are protected WMA files, they need to be transfered to the player using Windows Media Player, or another media player that transfers the licenses, and you need to use MTP mode to transfer them. Loading protected wma files directly on the card in the pc will make them unplayable. Some protected music(especially subscription music?) might need to be in main memory and not card memory to be playable.
If files are too deeply nested(ie. folders in folders in folders, etc.) the player might not see them. How many songs do you have on the player? They claim an 8,000 song limit, however if you have long tags, or path names, the limit might be much lower.
