Which operating system?
Which version of Photoshop?
Which version of Lightroom?
Which camera make and model are the Raw files from?
I have Lr 5
I have a mac
OSX version 10.9.5 ( i hate sistom. i rely solowed down my computer)
my camera is a canon 5D mark 3
The free, stand-alone Adobe DNG Converter is NOT a "plug-in".
It does not magically convert your raw images to raw DNGs.
You need to launch the application and run it on each folder containing your raw files in order to convert them to raw DNG files that you can then open in your version of Photoshop.
Note that the application does not work or see individual files, it works only on folders.
Always put each batch of raw files to be converted in a fresh, new folder.
If you run the Converter on a folder that contains raw files and already converted and adjusted DNGs, you will lose all the adjustments you have made to those already converted DNGs and the DNGs will be converted once again and overwrite the earlier, adjusted DNGs. You'll have to put in all that work all over again.