I think I messed something up on my lens.

You are correct that the switch locks the aperture. In order for your camera to function correctly in the auto-focus mode you must lock the aperture to the smallest opening (largest number such as f22). The switch has two positions. The position where the switch is lined up with the orange line is the locked position. When the lens functions properly and on the camera, the lens aperture is forced wide open by a pin on the camera body pushing a lever on the lens that opens the aperture. As part of the sequence when you push the shutter button, the camera releases its pressure on the spring-loaded lever on the lens, allowing the aperture to close to the setting that the "computer" has determined as correct. You will find this lever on the outside of the black ring that surrounds the rear lens element. With the lens removed, find the lever and make sure that with the lens set to the f22, sliding the lever counter-clockwise against the slight spring tension, the aperture opens wide and returns to f22 when released. If this is not the case, the problem is in the lens. If this works, then the problem is either in your camera body or in the alignment between the body and lens. If this does not get you on the right track, let me know what you find and we will proceed from there.