So I recently updated to the new launcher and heard about the new installers for mods. After playing around with the new items and horse breeding , I went and downloaded Forge, Builder Mod, and Gun Customization.(I downloaded all 3 installers, installed to 1.6-Forge-9.10.0.800) Then Minecraft just broke.
When opening it looked the same so I clicked play immediately but no mods were installed. I went back to the launcher and saw the profile was still my default vanilla one, so I switched it to Forge profile. Then the Play button unhighlighted and underneath my username on bottom left it said