I can’t hear ANY Minecraft music and/or Disks!

To begin, a long time ago I think in something like May or earlier (Before the nether update I think) I COULD hear the natural Minecraft music and the disks. But now I somehow CANT!! All I hear are those creepy effects (like when you go in a cave). I searched up this problem and it said that it would work if I deleted the Minecraft app and re-installed it, but I’m too worried if my worlds will get deleted because it said that might happen.