Random white cubes

So when I was loading in my world trying to blow up my world and when I won the command fill So when I was loading in my world trying to blow up my world when I want to command fill and then after I type in the command it said not outside the world but when I look left and right and walking around everything seemed out of place for the world generator to make random white cubes frozen mobs and And when I try to mine in creative mode I won’t even make a sound it’s just frozen but I can still break blocks it’s just a random white cubes