Problems with Reverse Macro Photography?

I use Nikon D90 with 18-105 mm lens. I recently got reverse macro ring but i'm not able to work with it. I used manual mode but when i look through the viewfinder i can't see anything. If i click image then it turns out to a blank image. If i use the lens normally then there's no problem at all.

Get your camera checked from care center

You need a lens with a manual aperture ring really, as you have to adjust aperture manually when using a reverser.
There's a lever at the back (on the mount) of all newer AF lenses which allows the aperture to be left open when using the viewfinder but stops the aperture down just before the shutter is tripped. If you don't have a manual aperture ring you'll need to hold the lever over with your finger, but you'll be stuck with maximum aperture.

You can't get into macro quite that cheap.

The reason you can't see anything is the lens defaults to the smallest aperture when it is off the camera, and that doesn't let in much light. If you take a photo and set it for a shutter speed of about 20 seconds, you should see something.

The problem is that you can't adjust the aperture on the lens. You need something like a 50mm f/1.8d lens that has an aperture ring.

But I have heard some folks have jambed a piece of cardboard into the lens aperture levers (one of those things sticking out the back of the lens), and force the lens into a different aperture, but that is all guess work, and seems too much time is being taken up in fiddling with such stuff rather than taking photos.

Your realistic options are:

1. Buy a 50mm AF-D f/1.8. This is the $130 lens, not the $200 AF-S lens (which will not work as it has no aperture ring). You should have a 50mm lens in your lens portfolio anyway, so this is not that big a deal.

2, Buy a set of Kenko extension tubes - the ones with the electrical contacts. They are around $200, and those contacts will allow you to mount your lens normally, and more importantly - to control the aperture with the camera. This will also allow you to use the camera's exposure system so you don't need to shoot manual if you don't want to.

But you will still have to use manual focus with either system. But macro shooters typically use manual focus anyway as most cameras are not that great focusing up close.

You can only shoot Wide open with reversing adapter.
You are seeing nothing cos it is out of focus (Extreme Bokeh)
But you can manually focus but wide open is too shallow for micro photography. Try 18mm wide end

Using a reversing ring is very difficult…

you can't see through the viewfinder - or liveview (if applicable)

you have to set the aperture to the narrowest (that is by default) and set the shutterspeed to about 1 second… To get enough light… Or use a strong external light source… So a tripod would be useful…

you could try using something else, like a bellows for the Nikon… Or buy a macro lens…