My nikon d3000 says I have my memory card is full, although I know its not

I have a nikon d3000, and I have never dropped it before.
Randomly it'll say that my memory card is full, but I know its not. I'll delete about 80 photos and yet it still says that the memory card is full. Now I can't take any new photos.

Format the card in the camera… Not your computer but your camera. Instructions are in your manual.
By the way, you need to format the card after every upload to prevent damage to the card.

I for m attend my new memory card but it as y s it's full a d it's not full

Why does my new memory card says it's full after formatting?