My screen resolution is messed up and we can't fix it in game

So my game was lagging, and we decided to turned down the graphics. We were goofing around with the settings and now our HUD is way too big to click anything or even get to the settings. I just need to know what to find steam files to change from a notepad file. Please help my game is goofed.

What i’m dealing with

Try changing the resolution of your game to your monitor size.

Could it be the UI Scale?

This post is a duplicate of Change Res. to 400x? and can't change it

The OP found his solution there.