How to open Nikon D3100 raw files using Lightroom 3?

How to open Nikon D3100 raw files using Lightroom 3?

You need Lightroom 4, Adobe stop updating the Raw Converter once the version has been updated, only the latest version of Lightroom will open the Raw files of recent cameras.

You can try and download the latest Lightroom 3 Raw Converter, the easiest way is to open Lightroom and go to Help>Update. This will connect to the Adobe site and download the latest version of everything including the Raw Converter.

If, after that is completed, you still can't open them (they just show as icons) Lightroom 3 does not support the Nikon D3100 and you will need Lightroom 4.

You'll need something like Adobe's Digital Negative and turn the RAW file into a DNG file…

The Nikon D3100 was made long before Lightroom 4 was introduced, like about a year and a half before

You just need to update Lightroom 3 to 3.6 (free update) and it should see your RAW files.