Thanks for the swift response.
I can get into RivaTuner in safe mode or when the driver's are uninstalled but it does not display the options for graphic card. For example the option for changing the refresh rate is available but the options for overclocking or restoring the card from what I have done is not available.
"Try uninstalling "Nvstrap" instead of setting the pipes back to what they should be."
I will try to do this but please tell me what does uninstalling "Nvstrap" has to do with my problem and what should I expect to happen when I do this?
By the way, Is there Anyone who knows a way to flash the graphic card's bios through DOS environment or in safe mode? I think if I can restore the original BIOS then the problem is solved.