Samsung Galaxy Note 2 — can't access music or videos on sd card

Possibly a read issue with the card. Try moving the files from your phone to pc, reboot, then move them back on. If that doesn't work move everything off the sdcard to your pc and format it, then copy back.

Have the same problem.
I have reformatted the card and reloaded mp3's
Have factory reset the phone (solved a battery drain problem with that)
It is visible and usable in my Netbook and Lappie and in a friends HTC.
If I reboot the phone it may read it until going to sleep but when it wakes it says that the SD card has been unexpectedly removed.
This started a month ago when I was getting an unusually heavy battery drain which I expect was an Astronomy app I had installed. A factory reset solved the drain but not the ext memory issue.

Have you tried changing the SD card, i look more like the problem is with the SD card not the device. I think you should use different SD card and put all the songs on that SD card and then try putting it inside the device and check if its being detected or not.

I was wondering if the 4.3 upgrade could cause the Note II to have problems with the SD card the way KitKat is doing to new phones, since it happened about the same time the upgrade from 4.1 downloaded and installed.