I just installed Optifine 1.12.2 with Forge. Now, when I go into video settings, everything says of.option? This makes it nearly impossible to use and I need a fix. I will provide a picture.
Step 1: Go into your launcher and find which profile you're loading.
Step 2: Go to the specified jar's versions folder. (ex:"1.12.2 > 1.12.2.jar & json")
Step 3: Open the jar in WinRAR or 7zip and navigate to "assets\minecraft\" and there should be a folder named "optifine", but since you're encountering this problem it most likely won't be there.
This folder should enclose two .properties files and another folder titled "lang" wherein it has the translated/converted text to use for the Optifine options so it uses plain wording.
Step 4: Download this folder "optifine" from sp614x's Github and place it within 'your.jar\assets\minecraft\'.
Should work now.