Thanks for your response. The fact that both music players (in fact, I downloaded and tried 4 in total, with the same result) are doing this is what baffles me.
I can see all of my music in the music player, which leads me to believe that it's looking in the right folder. I've randomly started clicking on albums and songs, and I find that a very few of them are playing, but most are not. This leads me to believe that it's somehow not reading the SD Card, or even worse, the SD Card is failing.
As for the charging problem, I suspect the charging adapters are failing, and are not transmitting the power as they should. I've tried charging with two USB cables, and both charge very slowly. I've noticed that it sometimes charges faster when I plug the phone directly into a phone outlet.