I took off my lens to clean inside the camera and now the camera will not autofocus or work at all??? there was a black mark showing up on pictures...

If lens was cleaned properly, you may have dirt on sensor.

This is not something that you can clean from the outside. It is probably on an inside element of the lens, close to the CCD. I would send it back under guarantee, along with some prints of photos showing the mark.

Try cleaning the contacts on the lens and camera body where they meet with a cotton swab lightly dampened with rubbing alcohol.

Check the aperature setting and make sure it's set to the red mark. It could also be that the contacts on the lens or the camera need to be cleaned. Alcohol is the best since it won't leave a residue, but a clean pencil eraser will also work.

Fix your issue with these steps:
1. Try forcing the lens to rotate a fraction of a inch. This will sometimes help the problem. Or simply move the switch from M to A on the lens.
2. Try to switching to a single of the 11 auto focus points. Then try if there are specific points that are the problem.
3. If all auto focus points are fine, try updating the firmware or cleaning the sensors inside the camera behind the mirror. If a one or more points are out of order, also try cleaning the sensors behind the mirror.
4. Detatch the lens from the camera, by applying pressure on the release button and twisting the lens so it can be released. See picture
5. Set the camera selection wheel to manual (M), see picture
6. Turn the camera on, and start the liveView format. This will flip op the mirror inside the camera.
7. Take a dry can blower. Or if in lack, use an empty plastic bottle, without moisture inside, and use it to blow on the autofocus sensors.
They are located at the bottom under the mirror. NOTE Do not blow with your mouth, small amount of moisture will hit the CCD also located here.
8. Turn the camera off
9. Reattach the lens. Push the lens, white point to white point and turn the lens in place.
10. This worked for me, hope it also helped you ;)

For more solutions check Nikon D80 Manual

The "err" is generally when you have the aperture set to something other than "F22" with the aperture lock on. As far as the lens, you should take a pencil and use the eraser end on the electrical contacts both on the lens and camera and ensure that they are clean. Often times, cameras will respond, but not fully, if some of the contacts have build-up on them. If this still doesn't work, take the lens to a camera shop or ask a friend to borrow their nikon and try using the lens on a different camera to see if it is indeed the lens or the camera. Doing this will help you determine which needs to go to the repair shop.

Oh This Could be a problem. But try just wiping it with a lens cleaning kit. If that dosnt work take it to a camera shop and let them work on it.

allow to dry for an extended period. leave lens off, put in dust free area.
it may 'come back' after a few days of being open.
moisture can cause malfunctions. is sensor clean a liquid? or air?
air can be driven by a propellant which can cause problems.
try removing battery if it does not come back, or maybe before.
good luck, otherwise, time for service'
mark

My Nikon was having the same problem with the stationary black spot. I used a can of Dust Off ( the original compressed gas duster). I just removed the lens and held the camera upside down (lens facing the floor) and blew my compressed air inside and my black spot disappeared. Just a thought you might like to know !! Good luck.

It appears that you have dust on your sensor that is recording in the same place on each image. It is a common problem with digital cameras. If you are adept at cleaning the sensor yourself, it is a relatively easy chore. However, if you have any doubts about it, take it to a reputable camera dealer and let them do it.