monitor Hz problem

i have a problem with my monitor,

when i start my pc it works ok, its going all ok but right after that windows logo with that bar green blocks going around loading windows, when thats over my monitor goes black, i think my Hz is set to high so it goes black, im not in save mode but i cant seem to find the nvidia setup window, its not right down in the menu not in start menu, it is in c: drive but no where to launch the setup window:s

anyone know how to fix this? my eyes will bleed in a few minutes since it using something like 60hz atm

btw i cant change it in the monitor itself

help me:<<< fastttttttt

thnx in advance