My 35-70 nikkor lense focus seems to be blocked by a screw inside. every time i shake it, i can hear the screw rolling inside it.

SOURCE: Nikon D40x AF-S Nikkor 18-55 mm 1:3.5-5.6 GII ED Lense Trouble

I've found the same thing with my D40x and the 18-55mm AF-S lens. I took a really close look at it and found that the mount on the lens is badly worn on all three of the bayonet tangs and one is cracked at the base. What happens in my case is that the lens has movement when mounted on the camera - just enough to stop the contacts from mating properly. Hence, no photos. Am taking it to Nikon to get it fixed. I suggest if this is your problem, that you take it to the repair man.

SOURCE: My camera lense will not focus automatically or manually.

There is no battery in the lens.  The lens receives power from the camera. Whether or not the lens is getting power, though, you should be able to focus manually.
When you say you can't focus manually, do you mean that you can't turn the focusing ring on the lens, or that when you turn the ring the image does not come into focus?
If you decide the lens needs to be repaired, I recommend sending it to Canon.  You can go to their website (canonusa.com if you're in the US), click on support, and follow the links.

SOURCE: Nikon DX AF- S Nikkor 18-55 mm lens won't Auto focus

Is the switch on the side of the lens set to manual or auto? Sometimes it's the little things like this that we don't notice.