The screen on my HP compaq nc8000 laptop goes blacks usually after the screen has been closed. the screen is very dark after is hardly visible except when squinting. does anyone know what the problem is or how to fix it?

The culprit will be the inverter board of your LCD screen that drives the backlight, my nc8000 shows the same symptoms after 6 years of heavy daily usage. After pressing the LID sensing button near the right hinge the backlight usually remains on, but sometimes you have to press it several times under a minute once it finally stays on. The proper fix would be to disassemble the screen and replace the inverter board, as the LCD and the CCFL backlight tubes are perfectly fine in my case.

On how to remove the screen from the laptop, you can get help from this HP guide:
http://bizsupport.austin.hp.com/bc/docs/support/SupportManual/c00803690/c00803690.pdf
(it's in section 5-35, that starts on page 128)

Unfortunately, I can't help you out on the other part, on how to disassemble the screen itself (but I suspect it has 4 or 6 screws under the rubber "feets" on its front), and I can't help you out in fixing the inverter board itself either...
If you want to fix the board yourself, you have to be able to wield the soldering iron perfectly, and your goal will be to replace some capacitors (they are usually bulging, so you can identify them being the culprit by the naked eye too).
The other option is to order a replacement inverter board, and simply swap the bad with the new one, it is still more economical than to buy a new display assembly as a whole; some chinese manufacturers are available, but I bet you can find some source more closely to your current location, just google for:
hp nc8000 inverter board