Please help! Messed up display settings and can't get a picture.

Hey all,
I just bought a big Dell 1080p monitor to run in dual screen with my old 1440x900. It turns out the new monitor doesn't work at all--I just get the white of the backlight and can't even display the monitors on-screen display menu.

In addition, in trying to get it to work I messed with the display settings in windows a bit too much. My comp detected the Dell, so I set it as the primary display, then when that didn't get it working I set it as the only display (stupid). Now I can't get any picture on my old monitor: even when booting I don't get my mobo splash screen or POST stuff, though the power LED on the monitor blinks rapidly from red (no signal) to blue (signal).

What can I do to get picture out of my machine? It's really weird to me that it's doing this, since I just changed a setting in windows and it's screwing me up before my OS even boots. I'm using a gigabyte x-58 mobo and a gtx460. Thanks in advance for any help!

Try starting the comp in safe mode
Uninstall the GPU and then do a clean sweep and reinstall after a reboot.

Before you do all that, Power up your system and go into the bios.
Then change the connector on the backside of the GPU to your old monitor , just exchange the connection...... see if it comes on... then you'll be able to change the other required settings.