try these, it might help.
First, download the latest driver from the intel website, and install it.
If the monitor still does not work, then go to your BIOS, then go to video configuration and change the graphics mode to auto or your choice i.e. the internal graphics. By that way , u can command the motherboard to use the internal graphics. Sometimes in the video configuration tab, the video card is set to external PCI or PCIE cards. So, then the internal graphics do not work.