Sounds like you may have uninstalled an nVidia display driver. That or the nVidia Chipset drivers that operate your motherboard.
Can you give us more specific details on your PC? Model number, video card installed? This way (if needed) we can direct you toward the right drivers to install.
IF Windows installed the proper drivers already, you probably just need to change your monitor resolution. You can do this by right clicking on the "desktop" and going into Properties.