When I hook my nexus 10-inch up via USB cable and try to open it up in my computer running Windows 7, I am able to view all files and have loaded music into the stock folder, but can't get the device to find the music and play it. Try using the app like stock Play music, Amazon MP3 player, Music folder player are not working at all. However, the Astro file manager does show up the songs. My music files are .wma format. That works fine on my honeycomb Samsung tab 10.1. How do I directly transfer them to tablet without WiFi network?
You can try the methods below to fix the issues.
* Making a reboot and then let the app re-scan for media files.
* The last android devices doesn't support .wma within these apps. You need to convert them to MP3 or flac files first.
* Download Poweramp trial version from Google Play and install it. Then you are able to listen music without any conversion.