I know it sounds like a stunt from a Peter Sellers movie, but I was installing a PCI graphics card on my Dell PC to take over from the onboard graphics controller, disabled the onboard graphics in the hope that the new PCI card would function - it doesn't! So, now I have no video at all - HELP!
You disabled the onboard graphics in the BIOS? Perhaps remove the pci card and take out the cmos battery for a few minutes or use the cmos jumpers as your manual recommends will reset the bios to its default settings, which will be the onboard graphics.
Doesn't help with the pci card thing but at least you may have video again.
I disabled via the Properties of the Hardware Management section - not via BIOS. Simply changing monitors does not re-enable the disabled onboard controller, I'm afraid. Will attempt the removal of the PCI card first - thanks for the advice...