Nikon D40 Turn camera on, and it used to display the photo I was ready to shoot. Had this feature for a few weeks, now I only get the menu and a black screen How can I get that display back?

Does the menu show when you press the MENU button? Can you see your pictures when you press the Playback button (right-pointing triangle)? If so, then there's nothing to fix.
The D40 works as SLRs have worked for half a century. There's a viewfinder which allows you to frame and compose your picture. The LCD monitor is for menus, camera settings, and picture review. LiveView, which allows you to use the monitor for shooting, is a recent development, which Nikon introduced into their cameras with the D3 and D300, both introduced years after the D40.

That's the way the D40 works. The monitor is for menus and picture review, not to show images before shooting. Nikon introduced the LiveView capablitily with the D3 and the D300, introduced after the D40. The D40 works as SLRs have worked for half a century, giving you the image through the viewfinder.

There's nothing wrong with your camera. The D40 works as SLRs have worked for half a century, using a mirror to project the image through the viewfinder. The live view feature is a relatively recent development among dSLRs, previously available only on point&shoot cameras.

You don't. The D40 works as SLRs have worked for half a century. Only more recent dSLRs (Nikon started with the D3 and D300) have the LiveView capability that lets you handle your dSLR as a point&shoot.

the d40 does not have live view. you would need to get a different camera.

while using slr cameras u always see in the viewfinder bcuz slr is a single lence refleime u can see the picture after shoot by clicking on play back option this is a feature of an slr camera

Please check that there is no debris on the contacts of the battery or the body contacts.  I suggest that you send it to a authorized repair centre.

You CAN!!! shoot in b/w with a d40, the only thing is you can't shoot in auto mode it has to be manual , aperture priority, or shutter prioirity. Go into menu - shooting mode - optimize image. you'll find it in there.

Most DSLRs (like the Nikon D50) don't have live view. In other words, in order to see the picture you must take it first.

About the auto review off, go to menu, "pencil" submenu, and the option is there (scroll until you see it)

With respect, you should read the manual. It's very comprehensive and needed. :)

The camera has a mirror lock up feature for cleaning the CCD sensor. You may have engaged it. Check your manual about this function