So, here's something odd. I discovered in applications manager (for the music app), a button that said 'uninstall updates'. So thinking that an update might be the culprit of the original issue, I clicked it. And it proceeded to not uninstall the updates but uninstall the whole app. So with that having happened, I went to the original folder I had created where I had transferred my mp3 files. I opened it and clicked one of the mp3s, and it played perfectly, and with the same exact control panel popping up that came up before the music app was deleted. So now I'm not sure what is actually playing the music files. It still won't play sequentially but now, with the music app gone (which up until this week I had never seen or even clicked on before), I don't have any indication what is playing the files nor any way to manage it. Hmmm. Wondering now if there is no hope of getting back to where I was before all this starrted or if I should try to download some other music player that will give me control.