GeForce 9800 gtx + control panel won't open

[zeroeleven]

I recently installed the latest driver for my GeForce 9800 GTX +,
when I was installing, my computer stayed on but my monitor went black,
saying there was no signal.
So I rebooted, and apparently it says my drivers are up to date now.
I tried to open my nvidia control panel via the desktop and get the error
"The NVIDIA display panel extension cannot be created: Possible reasons include:
Version mismatch. Reinstalling display drivers may solve this problem".
I tried reinstalling and got the same black monitor as before,
does anyone know why this is happening? Is there a way to fix it?
I tried rolling back the driver and got the same black screen as before,

PLEASE help me!!!

zero11

[KenB]

Try deleting the device from the device manager, reboot and let the system detect it again.