A big big help please

Please help, anybody knows how to restore a monitor settings? my notebook screen/monitor becomes black after windows logo, but still working, I can even shut it down using keyboard. It all started when a connect it to an external monitor, I change the settings of the notebook's monitor(disabled it) to extend my desktop icons and everything in my external monitor, unfortunately I wasn't able to restore the original setting after my work coz the notebooks monitor is no longer in the list, so I decided to restart the computer hopping the settings will be automatically restored, but it does not, I've tried several troubleshooting like removing the battery and pressing the start button for 30sec-2mins, I even used BartPE, I cant access task manager, it hangs up when I boot at safe mode, the monitor setting isn't in the BIOS/CMOS setup, all of this didn't work. Please help
Thanks a lot in advance, if you know how to please post here or at mail me at pleonador@yahoo.com