I have vivitar 35-105mm lens. My camera is Nikon d40?

What kind of adapter or ring or whatever should i buy so i can use the vivitar lens? The seller told me. That the lens has cannon connection. I'm not good at cameras guys.help me out please so i can use the lens even if its manual.

You got screwed - that's what you get for not being able to spell CANON. There's no way a Canon-fit lens can be adapted for Nikon.

Even the Nikon version of this lens would be pretty useless as it would allow neither AF nor metering.

The person that sold you that lens pretty much ripped you off. A Canon lens, be it the old manual FD mount or the new automatic EF mount, will NOT mount on a Nikon camera. There's no adapter to make it work.

You need to take it back and get your money back, or sell it to raise funds to buy a lens that will actually work on your camera.

Some old lenses have a t-mount for which there are multiple adapters available, but that seems to not be what this has. Whether the lens is the old Canon FD or the new Canon EOS, it is wider than the Nikon F, so you will not find a decent adapter. If there's any it will try to use a corrector lens to make it focus to infinity. That will further degrade the quality, which is probably nowhere as good as a new Nikon 18-105mm (or your old 18-55mm) lens anyway.

This would be an insult to your Nikon body

You have a Vivitar lens with a Canon mount. Your camera is a Nikon. They won't fit. Sell the lens and use the money to buy a NIKON-MOUNT lens.