Hello people. I want to know if there is a mod or a way to have look up and look down as mouse up and mouse down.

Did you mean the opposite perhaps? You just described normal mouse movement. You can inverse it (mouse down = look up, mouse up = look down) by checking "Inverse mouse" in the options screen.

I have an issue with the mouse up and down option. It just gives me other buttons but not the mouse up and down option.

SS2 controls are already set up like that , mouse up is look up, mouse down is look down.

unless you are talking about SS1.

What are you really asking for, and what are you talking about in this post? If you enable "Invert Mouse", moving the mouse up/forward will lower the view, while moving the mouse down/back will raise the view. Disable "Invert Mouse" and you will have standard FPS controls where moving the mouse up raises the view and moving the mouse down lowers the view.

The "Invert Mouse" option is on the first screen of the options menu.