First check to see the plug that connects the LCD to the computer and the
computer to the LCD, is not loose and is connected properly. Then check the
power plug connection.
Next ensure that all videocard drivers and LCD drivers are up to date and
installed properly. Then ensure that the settings for the videocard and LCD
are set properly for desktop and any programs that you are running and having
trouble with. Then if this does not help it is most likely that you have a
hardware problem and need to test if it is your videocard or LCD screen that
needs to be replaced.
To test this just try running your LCD screen on another computer and the
videocard on another computer, not both at the same time. This will indicate
which peice of hardware needs replacing.
I hope this helps, please note this advice I have given might not be correct
as I am not an expert but I think it will help you.