Most raw problems are either file in wrong folder, or more than one file in folder. OS?
As Curt Y mentioned, either your ACR plugin is in the wrong location, or you have more than one ACR plugin for your version of Photoshop and they are conflicting.
With the DNG coverter, it is important to understand that DNG converters only works on folders that contain raw files.
Select the folder and then convert. This will convert all the raw files within the folder.
If you ry to use DNG converter to open the folder to select individual files this won't work.
Select the folder not the individual files.
Where should i search for ACR plugin. When i check for plugin verison in PS, it says 8.3.
Also, for DNG i am selecting folder that contains RAW files, it does not have option to select individual files.
In PS if you click Help/about plugins/camera raw it will give you version.
Have not used DNG but believe you convert the folder, and makes a new folder for DNG files.
Yes, I follow the same steps and it says 18.104.22.168. But it does not open my NEF files.
The current version of ACR is 8.4.
How did you download the photos? If you used old Nikon software, this might have corrupted the raw files. Update your Nikon software or use a different method to transfer your images. Fix your broken files with this http://owl.phy.queensu.ca/~phil/exiftool/fix_corrupted_nef.html
Its working now, yes I was using Nikon Transfer 1.
Thanks again for your valueable help