I can't download any SD pictures into my computer?

All it reads is: " no pictures or videos were found " and i have pictures in the camera, the camera is a NIKON D40 and everthing was fine, I even plugged in the cable to do it as a different way but this does not make a difference, STILL NO READ, and I'm about to toss the computer away. I'm going crazy… CAN ANYONE Help ME Please… WHY IS THIS DOING?

Here are some thoughts

1 an sd card should be formatted in a camera and nowhere else
2 if a pc ever modifies an sdcard in ANY way then the camera may reject the card… A pc might create thumbnails if an UNPROTECTED sdcard is VIEWED in a pc… Like a SLIDESHOW for instance
3 a card has a write protect switch for a VERY good reason. If you eject the card, use it.
4 turn off the camera before attaching a usb cable, plug in the cable to the pc… Turn on the camera. Note: some cameras have a menu option to DISABLE pc connection.
… Some even have a menu option to CONNECT to pc. Learn YOUR cameras menu options.
5 sometimes people forget they have more than one camera(phone also) that they have… Installed USB connection software for. This software may HOGG that socket for just… That ONE device.
6 if the camera can see the photos, then they should still be there. Using the USB lead… Try the camera in a different pc.

if all else fails you could just try reading the D40 manual, Nikon's
can be made to produce RAW and JPEG files.