Audio files not playing on computer after syncing sandisk

I just recieved my Sandisk Clip Jam today, I have transferred some audio files to the device and most on them play (although it says it can’t read some of the files). HOWEVER… now files are not playing on itunes on my PC and when I went into a folder of audio files to try them out on Windows Media Player, the files will also not play… HELP!

Can’t help until you tell us more about the files (format, source, etc.), & it would also help to know the method of transfer to the player (iTunes, WMP, copy/paste through Explorer, etc.)

The problem seemed to solve itself, but now I have just added some more files and now (after correctly ejecting the device) I cannot open the Music folder or the Settings folder etc

SYNC = SINK!

Use copy and paste to put folders of songs on your Sandisk player.