Hi,
Here are some details on my computer:
Toshiba P100 SD 802F
Video adapter : Geforce 7900 GS driver 8.4.0.0 (original driver)
BIOS : 3.8 (latest driver)
All other driver are original
Windows XP media center with SP2
 
My problem is that Windows do not detect my laptop screen, only any external CRT or LCD I connect to it
 
How it start :
I install software MagicTune version 9.1.0.429 witch is coming from samsung when you buying their external LCD display 226BW.
Install complete and ask to reboot
Just before reboot, a message error say that MagicTune could not install correctly.
Reboot computer and my laptop LCD is black but I can see it is powered because it is not the same black as when the laptop is close.
I plug my external LCD display and it automatiquelly show my BIOS password screen on it but not on my laptop screen.
 
I can boot normally and do everything with my external screen but in the menu configuration (Display properties setting), Windows do not detect my laptop screen.
 
What I did after :
I uninstall MagicTune
I run Mc Afee, AD Aware
Try key Fn + F5 and no effect except external screen goes black and come back (This is my key to stich between screen configuration)
I check with nvidia tool for clone screen and other setting
I check with display property, only detect the external screen
Desinstall nvidia driver, reboot and reinstall original driver
Start in safe mode
Check my BIOS and put setting dual screen on boot
I updated my BIOS from ver 2.0 to 3.8 (latest version)
Go back to earlier windows restore point
Complete format of harddrive and new windows installation
 
After format I still have all the same problem, no laptop screen for bios and in windows just on the external monitor.
 
I think I may have a problem with :
- the bios of my graphic card
- a cable to my laptop display have get disconected
- the laptop display is dead
 
But I don't know how to upgrade the bios of my graphic card... No bios for graphique card at toshiba web site :
http://support.toshiba.ca/support/ [...] Model.asp#
 
Thanks in advance for your help

Sounds like your laptop display is dead.