Help importing pictures on computer?

Okay, so I have a Nikon D3200 camera, with a 32GB SD card. Every time I plug the card into the memory card slot on the side of the computer, a dialogue box pops up asking me options to import pictures. I follow the common motions, tag the pictures, etc. Have done so over 30 times, importing a little under 3,000 pictures in total. However, the other day, I plugged the SD card into the computer and accidentally closed the dialogue box. I can't get it to come back. I have taken the card out, wiped off the connection points, and done so to those in the card slot in the computer. I have turned the computer off and back on. I plugged it into a friend's computer, the dialogue box came up, and I could import them. Can somebody help me figure out why this box won't come up anymore? My computer doesn't even recognize that the SD card is plugged in anymore. No it has not been dropped or damaged. It all simply stems from me accidentally closing the box out. I could really appreciate the help. I'm bad with computers, and absolutely can't figure it out on my own. I have comsulted Windows help, and it gave me absolutely no solutions. I have 300 photos from a recent grad party that NEED to be dumped onto MY computer as soon as possible. Please help

Added (1). Is it possible the card was denied access in security settings somehow when I closed out the dialogue box? If so, how would I go about resetting this (possibly restoring defaults or allowing the card access)?

Go to your friend and copy the photos to their computer, then copyback out on removeable media like a USB stick.

You say your PC no longer sees the SD card, so that means you can't use the Windows tools to repair it. So that leaves data recovery for which you could download a free program. You many not get all of them back.

Once the photos are secure, format your SD card in your camera - never in the PC. You can look for photos simply with Windows Explorer. They are usually in the DCIM folder. Just copy and pase.

The simple solution is to buy an external USB card reader. I've never had good luck with the on board card readers in any of my computers so I always use an external. The nice thing is you simply go to explore,
copy / paste the files to a folder of your choice and you're done. This happens because your computer will see an external reader as a hard drive.

First off, I'd get a 4 or 8GB class 10 memory card. You only need 32GB if you're doing video.
Secondly, for about $8, you can get a memory card holder at most of your big box stores. It will
plug into an open USB port.

Just use your computers file manager, open the memory cards file folder where you images are located and copy them to a new file folder on your computer named for the subject/location and date. That way you can find the images again, much later.

As mentioned, use a card reader and take control of your images and where you put them

Are you formatting your card in your cameras after you copy all the images to your computer? You need to do this routinely otherwise you will eventually end up with a corrupted memory card. Forget that your camera has a delete button.

I never use the dialogue box to import photos. I do this:
Plug in the card and delete the pop up dialogue box.
Go into "My Computer"
You should there see your hard drive, DVD drive and another one which will say something like Media card; you will see a blue line indicating how full the card is.
Click on that and all your photos will be there.
Then copy and paste to where you want them.