I didn't quite understood what you said.
But anyways, are you saying that you can't install Forge? If so, click this link, this will bring you to the Forge website. On the left side, you will be able to pick the version you wish to install.
Go to the official download site:
At bottom, select 1.12.2 and download all 3 mods
Replace all 3 mods with the current ones you are using