@LucyInTheSky: Please can you confirm the model number and current Android version of your phone, located in Settings > About phone? Have you tried checking the Google Play Store for any updates for Spotify? When you say that "everything has disappeared", what exactly are you referring to? As a basic troubleshooting step, please try pressing and holding the Volume Down and Power buttons together until the phone restarts, as this will refresh the software and address any temporary performance issues. Don't worry, this won't affect your personal data or settings.
I wasted yesterday trying every resolve I could find until I found this solution. Thanks, issue partially resolved. I can see and play music again, but I still can't use my SD for spotify storage without losing everything again. I will try reformatting it tonight to see if that helps. All over a samsung update🤦♂️