Nikon D70 Folder contains no images, but the card is full?

I desperately need help. I've been taking pictures for the past two weeks and have no problem with the card until now. This morning I was taking pictures of my little baby sister, had no problem looking at them at that point. Then I went to show my mom and got that error of "folder contains no images" not even 10 minutes later. I then tried to connect the camera (via usb) to my laptop to see if I could get them off there, I've had no problems doing this until this morning, and then I got the error of that the disk was not readable by my Mac. Can someone help me with this, I don't know what went wrong? I'm just so upset over this because it has some very important photos on it.

Thank you if you can help me with this!

Added (1). The usb is the only way for me to put the pictures on my computer. I forgot to add that, sorry!

There's a problem in your handling of your images

Remove your memory card and insert it into the card reader on your computer

Use Finder to copy all the file folders from your card to your computer. Unless you accidently deleted all your images while the card was in the camera or formatting the card in the camera, all your images should be on your computer.

Did you format your memory card after the last successful time you copied all your images to your computer his morning?

If there are still no image files showing up on your computer, that could mean that your card has become corrupted. That is usually caused by deleting images on a memory card and rarely or never formatting the card using the format feature on the camera

For now, STOP using that card and use a different, freshly formatted, memory card.

Using the free program published by Transcend called RecoveRX. Run that with your card in the card reader on your computer. It will recover the images and place them to a file folder on your computer that you either have made or the default file folder used by the program.

Once you have recovered your images, format the card using the format feature on your camera