Today, I installed Windows Vista on my laptop (it has two graphics cards - HD 3k and NVIDIA GT 620M)
When I installed drivers for HD 3k and rebooted - it showed me blank screen. I can control system (like typing pass, hearing it's responses, etc) and adjust brightness of this blank space by FN-keys. When I remove the driver, all is normal.
How can I make this graphics card work?,
Computers with two graphics Controllers, like in your case Intel® HD Graphics 3000 and the NVIDIA GT 620M, are computers that requires special drivers configuration to make the Switchable function work.
Note that we as Intel® provide the hardware to the system manufacturers (Dell, HP, Toshiba, etc...) and they will design and create custom drivers specifically for their computers. We are able to provide generic drivers for the OEM systems; however, since you have a switchable graphics computer, the driver that will work with your computer needs to be provided by the system manufacturer.