How to manually adjust the aperture in video mode on the Nikon D90

You must lock the aperture ring to f/22, so the camera can engage the aperture adjustment lever on the lens. Then, you can change the aperture with the command wheel.

When you change the aperture with the command wheel the aperture ring on the lens doesn't move when the camera actually adjusts the lens aperture.

Take the lens off and locate the aperture adjustment lever on the lens mount.

Unfortunately, this won't work with older AF lenses. So if you are using an older lens, the only thing you can do is change the camera setting to M (Manual) to adjust the aperture on the lens yourself.

Yes. I have one and it works perfectly on my D90. If you get the version with an aperture ring, be sure to set the aperture to its smallest setting (f/22) and lock it. You control the aperture from the camera, the same way as on a lens without an aperture ring. If you get the version without an aperture ring, don't worry about it.

You need to turn the aperture ring to its smallest aperture (f/22) and lock it using the little orange slide. Control the aperture from the camera, just as you do with the kit lens.

Make sure you set the aperture ring on the lens to its smallest setting (largest f/number) and lock it. Without doing so, the lens will not communicate properly with the camera and thus you will not get the autofocusing.

Check to see that the lens aperture ring is set to the smallest (largest numerical) aperture setting (usually f22 or such). Nikon AF cameras have to have their lenses set at the smallest aperture for most of their program modes to work. Nikon AF lenses have a small slide or twist lock adjacent to the aperture ring to lock it in place at the smallest aperture. This may have been unlocked during the cleaning.
Another possibility is that the lens's electrical contacts were damaged during cleaning, so the body is not "seeing" the lens. Do you have another lens you could attach to the body to test this theory?