Hello,

It is because you turn off the onboard vga device in your motherboard that is why you don't have anymore display in your monitor. This will happen often if you don't have a separate video card in your system and you only use the onboard. To solve this problem, you should reset the bios of your motherboard. To do this refer to the motherboard manual.

as you have lost your display and cannot see the options in the bios, I would suggest that you reset the boards bios back to factory settings. To do this, switch the machine off and pull the power plug out of the wall. Then open the case and look for the small battery on the mainboard. Close to this battery there is a small jumper switch which has three pins with two of them connected by a small black link. It will also usually be written on the board close to these pins, what they are and how to connect them to reset the bios. If you cannot find these pins, then remove the battery ( very carefully) and leave it out for about a minute. Replace the battery, refit the case, plug the power cord back in and boot the machine. You may get error messages telling you that the date and time is incorrect. Go into the bios, reset the date and time and then save and exit. Dont change any other options yet. reboot the machine and ensure your display has returned. If this does not work, then you may have to take the machine to your local repair shop for expert service.