Plug the vga cable into the port built-in to the motherboard (that should give you your video back on your monitor). When turning on the computer, you need to get into the BIOS.
This is done by pressing either F2 or F12 at the Dell logo screen.
After you get into the BIOS, you need to find your video settings.
Depending on which BIOS version is present, it could look like this.
You need to find an option that says "Video". From there you need change the primary video adapter from "IGP" or "Onboard" to "PCI".
After you do that, you separate video card should display like it did normally before updated the BIOS.