Display lost after changing the resolution in Linux

I have change the resolution from 800x600 to 1024x768 and restarted the computer. Then the display didn't come out and could not able to do anything.

Have you ever encounter this problem?

So to get the display back with previous settings (ie. 800x600) follow the following steps.
1) Open /etc/X11/xorg.conf
2) Edit the following section as nessary.
Section "Screen"
Identifier "Screen0"
Device "Videocard0"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 16
Modes "800x600" "640x480"
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 24
Modes "1280x1024" "1152x864" "1024x768" "800x600" "640x480"
EndSubSection
EndSection