My Nikon D40 18-55mm lens won't work on automatic

Yes, as long sa the lens can fit the bayonet. But it can't focus, because there are no AF motors in Nikon D3100 and AF 70-300mm f / 4-5.6 - G. And Nikon lens with AF is without AF motor. Lens marked with AF-S have focusing motor

Could you be a little more specific about "does not work"? Does the lens not fit? Can you not view through the lens when it's attached? Does it not autofocus? Does it not meter the exposure properly?

Yes and no. It will fit and you can take pictures with it. You'll have to focus manually, of course, and you won't get any exposure help from the camera's light meter. You'll have to use the camera in the Manual exposure mode, setting the shutter speed on the camera body and the aperture by turning the ring on the lens and, as I said earlier, without any help from the camera's light meter.

Just a thought - are your Image Stabilizer and Auto Focus switches On or Off?
Might be worth experimenting with them.
Otherwise, sorry, can't help.
May be necessary to contact your vendor.

The filter doesn't go onto the camera, but onto the lens. Assuming it's the proper size, it should just screw into the threads on the front of the lens (the end away from the camera). If the lens hood is on, remove it first.

Yes and no. I assume the lens is of more or less the same vintage as the N75? If so, the lens will fit onto the D5000. All of the camera's exposure and metering modes will work properly. However the lens lacks an interal focus motor and thus will not autofocus on the D5000. You can focus manually, and the green focus indicator in the viewfinder will continue to work.

the les coattings might have damaged due to uv filter broken,better get it the lens serviced.

The Canon lenses are FD mount which means that you will need to get an adaptor to convert the FD mount to fit the F mount on the Nikon. An example of the mount can be seen here:

http://www.rugift.com/photocameras/canon-fd-nikon-adapter.htm

As for the speedlights the hotshoe mount will accept them on your Nikon, put them on with fresh batteries and try them out.

I bought a 4 lens kit - I think from Amazon. It was a long time ago.
The size is 28mm.
yes, here it is
http://www.amazon.com/Nikon-28mm-Filter-Set-Coolpix/dp/B0000521B9

Get a CLA-1 lens tube. It screws into the camera body. The other end accepts 43mm accessories. Put on a 43-49mm step-up ring. Into that screw a 49mm UV filter. (The step-up ring is needed to separate the filter from the extended lens.) Leave the UV filter on at all times. Throw away the lens cap.