Problem LIGHTROOM

What are the Settings in Develop??

Then you may of accidentally set the Develop Defaults to darken the images of your nikon camera.

When you say it look good on a notebook in what program is it you are viewing the images in? 99% of all other program that may display RAW file data, as a viewable picture, are using the embedded JPG inside the RAW file to do that and NOT the actual RAW data.

There are setting in Nikon cameras that make the JPG version of image you take appear brighter than they really are. One of them IIRC is soimething called D lighting. If you had that set in the camera it will make the embedded JPG image that is inside every RAW file look brighter until LR creats it own Preview from the actual RAW data. When nthat happens the images will look darker as the in camera setting are not used on RAW files.

So check your camera for those settings.

Although the image you posted looks dark it is not Black.

Please explain in more detail what your problem is, what camera you are using, are you shooting RAW, the OS you are using and the exact version of LR that is installed on your system.