I have an old Sansa mp3 player and had the same problem where the power button became unresponsive. I was able to fix it by rebooting the mp3 player.

Here's how to reboot all the Sansa models (copied from the Sansa website):

Resetting a SanDisk MP3 player
My SanDisk MP3 Player is freezing up. How do I reset my SanDisk MP3 player?

If your Sansa player is freezing or not turning on, the first thing to try is a reset. This will clear any temporary condition that may cause the player to freeze or not shut off completely.

Resetting a Clip Sport Go
1. Press and hold the Power/Center Select button for approximately 20 seconds.
2. Release the Power/Center Select button.
3. Press the Power/Center Select button again to turn on the player.

Resetting a Clip Sport Plus
1. Press and hold the Power/Center Select button for approximately 20 seconds.
2. Release the Power/Center Select button.
3. Press the Power/Center Select button again to turn on the player.

Resetting a Clip Voice
1. Press and hold the Power/Center Select button for approximately 20 seconds.
2. Release the Power/Center Select button.
3. Press the Power/Center Select button again to turn on the player.

Resetting a Clip Sport
1. Press and hold the Power/Center Select button for approximately 20 seconds.
2. Release the Power/Center Select button.
3. Press the Power/Center Select button again to turn on the player.

Resetting a Clip Jam
1. Press and hold the Power/Center Select button for approximately 20 seconds.
2. Release the Power/Center Select button.
3. Press the Power/Center Select button again to turn on the player.

Resetting a Clip Zip, Clip+, Sansa Fuze+, c200 series, e200 series, or e200R series player:
1. Press and hold the Power/Menu button for approximately 20 seconds.
2. Release the Power/Menu button.
3. Press the Power/Menu button again to turn on the player.

Resetting a Sansa View, Fuze, or Clip player:
1. Slide and hold the Power switch up for approximately 20 seconds.
2. Release the Power switch.
3. To turn the player on, slide the Power switch up then release instantly.

I use phonograph for years now but not sure about the folders or maybe in the premium version you have folder but you ca create playlist so you don't realy need this option

Thanks, but in my case it's not that it's unresponsive. It's physically broken.
I can create playlists in the new Sandisk too. I specifically need folders, not playlists.

ZFR, I think you got bamboozled by a joke post; he mentioned a Phonograph, a really old timey record player.

Ah, OK. I know what a phonograph is, but I thought it was the name of an app too. It wouldn't actually be a bad name for one.

it is.

non-bamboozle thyself!

https://play.google.com/store/apps/details?id=com.kabouzeid.gramophone&hl=en&gl=US


Edit: I was also looking for a dedicated mp3 player this time last year. nothing amazing, but all the optons i found with the features I wanted were rather dodgy chinese versions (some with amusing reviews).
ended up with a new phone instead which does rather a good job but ill be interested to see what you find.

Yeah, it seems about two thirds are those now. I actually considered getting one, with the assumption that it won't last as long but will be cheaper anyway, but if I'm spending that money, might as well try the phone first.

pretty much what i did.

This Intenso Music Walker has a Shuffle Folder option, among others. The best thing about it is, it works with AAA (rechargeable) batteries. The audio quality is about the same as the typical Realtek on-board sound card.

I've still got my Creative MuVo MP3 player (512Mb) which supports shuffling of mp3 files, and is decent.

Although i'm sure you're looking for something more recent and something still on sale...