Autofocus does not work after cleaning canon 55-250mm lens

SOURCE: 70-300DL Macro Super autofocus problem

It is likely that the lens will need parts. Sigma is not the best for repair parts. Typically, the small nylon gears that control the AF break. It is still a useful piece in manual focus. Repair costs would likely exceed its value.

SOURCE: Nikon 18-200 autofocus lens won't

OK I just fixed it, thanks to Ken Rockwell.com who says:

"Once in a blue moon my Nikon 18-200mm won't focus on my D200. Manual focus works fine, but the lens won't autofocus no matter what I do. It's annoying!
Of course the camera needs to be pointed at something with contrast, lines or texture. Point it at the sky and nothing autofocuses. That's normal.
One time this was so bad I thought for sure I was going to have to send my lens in for service, since nothing would get it to go.
Then I discovered the problem: I had knocked the AF switch on my D200 to M. This switch is easy to knock and I had forgotten to check the obvious. There also is a switch on the lens which is not easy to knock, but I have left the lens set to M shooting at night, and I forgot to return it to A/M the next morning.
This fixes most of my problems.
Rarer is when the lens honestly won't focus. When this happens I turn the camera off and on. If this doesn't fix it, turn the camera off, press the lens release button and rotate the lens back and fourth a couple of times. This will clear any dust off the electrical contacts and focus returns."

SOURCE: autofocus function will not work on Canon 17 40mm 1.4 EF lens

Since the problem is limited to this lens, I highly doubt that you would have to replace the cameras AF sensors.
Since you only have the problem with this lens, I am afraid that you will have to get the lens repaired. Is the lens also 3 years old? Did you get it with MACK extended warranty?
Sometimes, Canon do these kinds of repairs for free, if they discover that there was some manufacturing error that caused it to fail. So be sure that you get it to a certified canon workshop. 
I hope this helps, 
/Chris

SOURCE: Nikon d40 18-55mm lens will not auto focus.

the nikkor 18-55 lence is no longer u can chage the ed lence into vr lence is upcomming with nikon d3000 mout the coast of the lens is 200$

SOURCE: Canon EOS 5D Autofocus will not work.

ho.....ho...
I have this prob in my canon EOS kiss SLR.
CHECK THAT>>>>>>>
Hold the camera vertically.Switch on the AF and let the camera to auto focus.!!!!!!!!!!!!!!!!
Don't wondering....Check ur camera's sub mirror in the in side of the sub mirror.The spring that push back sub mirror from the main mirror is broken.......!
How to repair this? Follow this link....
http://www.facebook.com/home.php?#/album.php?aid=2042115&id=1359757176
bye..