not working

bigg = 20
spritex = 0
spritey = 0
slimespeed = 1
camerax = 0
cameray = 0
sprite_names = ["front", "back", "unused", "left", "right"]
current_sprite_name = sprite_names[frontbackleftright]
frontbackleftright = 1
end
update = function()
  if keyboard.LEFT or gamepad.LEFT then
    spritex = spritex - slimespeed
    frontbackleftright = 3
  end
  if keyboard.RIGHT or gamepad.RIGHT then
    spritex = spritex + slimespeed
    frontbackleftright = 4
  end
  if keyboard.UP or gamepad.UP then
    spritey = spritey + slimespeed
    frontbackleftright = 1
  end
  if keyboard.DOWN or gamepad.DOWN then
    spritey = spritey - slimespeed
    frontbackleftright = 0
  end
end
draw = function()
  screen.clear()
  screen.drawMap("map2", 0, 0, screen.width, screen.height)
  screen.drawSprite(current_sprite_name, spritex, spritey, bigg, bigg)
end``` why aint this workin´, i mean the sprite doesnt change appearance

You never update the current_sprite_name in your update function, only the frontbackleftright one.