[ubuntu12.04] Dual Monitor suddenly doesn't work

[satang500]

I could setup dual monitors using nvida-settings.
When I first set it up, there is a smaller disabled monitor right next to the main monitor in nvida-settings-->X Server Display Configuration --> Layout, and I enabled the smaller monitor with two separation X screen with Xinerama options. (I'm using two ViewSonic monitors.)

I could use the dual monitor without problems, but after I reboot my pc today, it doesn't work anymore. The second monitor was gone!!!
I googled it and did everything I could ( I uninstall/reinstall nvidia driver and x.org, change /etc/X11/xorg.conf and so on), but nothing works!!!

I think the main problem is that there is no second monitor (regardless of disabled or not) in in nvida-settings-->X Server Display Configuration --> Layout !!!
I think once I could see the second monitor in nvida-settings-->X Server Display Configuration --> Layout, then I can set it up again.

I attached two image file: nvidia_settings_2.png (which is the initial status right after installed ubuntu12.04) and Screenshot from 2012.png (the current status). FYI, please ignore the name of the monitor since I grab the first image from the Internet, not mine.
Please HELP!

I also attatch my xorg.conf as follows.
================================================== =====================
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 295.33 (buildd@allspice) Fri Mar 30 15:25:24 UTC 2012

Section "Monitor"
Identifier "Monitor0"
VendorName "Unknown"
ModelName "ViewSonic VX2450 SERIES"
HorizSync 24.0 - 82.0
VertRefresh 50.0 - 75.0
Option "DPMS"
EndSection

Section "Monitor"
Identifier "Monitor1"
VendorName "Unknown"
ModelName "ViewSonic VX2450 SERIES"
HorizSync 24.0 - 82.0
VertRefresh 50.0 - 75.0
Option "DPMS"
# HorizSync source: edid, VertRefresh source: edid
EndSection

Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
Option "TwinView" "0"
Option "TwinViewXineramaInfoOrder" "DFP-0"
Option "metamodes" "nvidia-auto-select +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection

Section "Screen"
Identifier "Screen1"
Device "Device1"
Monitor "Monitor1"
DefaultDepth 24
Option "TwinView" "0"
Option "TwinViewXineramaInfoOrder" "DFP-0"
Option "metamodes" "nvidia-auto-select +0+0"
SubSection "Display"
Depth 24
EndSubSection
EndSection

Section "InputDevice"
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/psaux"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
Identifier "Keyboard0"
Driver "kbd"
# generated from default
EndSection

Section "Extensions"
Option "Composite" "Disable"
EndSection

Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
Screen 1 "Screen1" 1920 0
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
Option "Xinerama" "0"
# Removed Option "Xinerama" "1"
EndSection

Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "Quadro 600"
BusID "PCI:3:0:0"
Option "NoLogo" "True"
EndSection

Section "Device"
Identifier "Device1"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "Quadro 600"
BusID "PCI:4:0:0"
Option "NoLogo" "True"
EndSection
================================================== =========================

[dvn3ch]

Without sounding insulting...Did you click on the dual arrows on the right side of the "Disabled" text box? There you should find Separate X Screen & TwinView choices.

When I originally saw this post I thought that Nvidia did not show your other attached monitor. That would have been a little different. If you fix your problem, even if it was advice from another person or site, please reply back with the solution and change the status to solved. A headache for you can be a savior for many others. In time, the favor will be returned.:p