Nikon d40 not taking pictures?

I push the button, flash comes on but it just clicks and nothing else. If i slide switch to manual it will take a picture… I don't understand.

Probably auto focus, if the camera can't find focus, probably due to lack of light, it won't take a picture, selecting Manual forces the camera to ignore metering and auto focus. Try it on manual focus.

Just a guess.

Here's an experiment for you and perhaps you've done this.

Go out in the sun and shoot. What happens? Taking photos?

Go inside with very low light, what happens? Not taking photos?

If that's the case then you'll know the above is correct. I agree, if the camera can't find focus it won't fire - simple as that. I would suggest there's probably nothing wrong with the camera but with the way you're trying to use it.

If the switch you are talking about is on the lens, then you're having focus lock problems.

In order for your camera to take a picture, it must obtain focus lock. You can see if the camera has focus lock by observing the green light in the lower left of your view finder.

Things that cause focus lock issues:
* You are too close to your subject. For the 18-55 kit lens, this is 11 inches from the subject to sensor plane which is close to the rear of the camera body.

* You are trying to focus on something that lacks contrast. The camera won't auto focus on a blue sky or a blank smooth wall.

* It's too dark for the camera to focus. Be sure your focus assist light is enabled.

* Nikon's kit lenses seem to have dirty contact problems. Rotating the lens gently back and forth, like you're trying to remove the lens without depressing the lens release, will often clear up this problem. I have seen this issue on the 18-55 and 18-105 lenses on the D40 and D90. This is a pretty common problem.