Hello, I am Pete, and I'll be happy to assist with your question today.
If you have another computer available, you can try connecting the Nikon camera to it and check if the computer can see the camera. If it cannot, this confirms that the problem lies with either the USB cable or the camera itself.
Given that you were having issues with the Nikon connection before and had to try 2 or 3 times to get it to connect recently, it does seem that the connection has now given up. Over time, the terminals on both the USB cable and on the USB connection on the camera itself will wear out.
First, try using a replacement USB cable. If that does not work, then the USB connector on the camera itself will need to be replaced.
You can get a replacement USB cable here:
I'll check it out -- thanks. If the problem is in the USB connector on the camera, is a repair possible? It's only a $100 camera.