D3 will not show option to do firmware upgrade from 1.0 to 2.02

SOURCE: Nikon D50 LCD Display does not work

NatD, The D50 and indeed most SLR digital cameras [ I have a D40 ] does not allow you to take pictures using the LCD display ... this is by design, you are meant to use the viewfinder and the image you see through it is straight through the lens via a mirror block [ called a reflex pentamirror or prism ]. When the mirror is down such that you can see the image in the viewfinder it is obscuring the sensor [ the bit that takes the picture ] and when you take a shot the mirror lifts and the picture is recorded. Its this reason that DSLR's dont use the LCD to shoot, however there are a few now available that do let you do this, such as olympus, new panasonic one and higher end Nikon and Canon cameras. Hope this explains it without getting too detailed!

SOURCE: Nikon D200 problem with SIGMA 28-200 lens - works on one D200 and not my other

Sigma lenses sometimes need re-chipping for full compatability with certain Nikon camera. They are usually quite good about doing this gratis.
Try the Sigma on another body at the camera shop or at home (preferably and older AF film camera). If it works then its likely just a chip compatibility issue.

SOURCE: Can a SDHC card be used with a CF card adapter in Nikon D70s?

You would have to get an SDHC to CF adapter which could be pricey and they are hard to come by.

SOURCE: I need a master reset, hard reset, firmware reset

Two methods...scroll to "reset" in the setup menu and follow the on-screen instructions. -or- Remove the card and battery...press all the buttons...leave the camera alone for 20 minutes...insert the card and then the battery...turn it on.

SOURCE: cannot get ml-l3 remote control to work on nikon D90.

The two batteries are the ones in the remote? Make sure they are installed correctly. The camera will need to have a decently charged battery as well. Put the camera in P mode, pop up the flash and allow to charge. Make sure you pre-focus the camera on one subject or near the subject. The remote is supposed to focus the camera, but the camera may not fire if it cannot focus or if it needs the flash.

And most importantly make sure you are setting the camera drive button to remote so the camera knows to work off the remote. This button is in the upper right hand side on top and you will press the button and turn the control dial until the remote symbol appears. The remote should be pointed at the camera and will work best if you point it at the remote sensor on the front right side. make sure the strap or nothing else is obscuring the sensor.

If non of this helps, you may have a bad remote. Contact your retailer for a replacement