After you have opened your Raw files and then want to safe them go to File>Save As and in the dialogue box that opens there is a drop down menu, which, by default, will be PSD, Adobe native format, in that drop down list are all the file formats that PS recognises, you'll notice that .raw isn't one of them, you just made that up.
Your original Raw file (NEF, CR2, PEF etc.) will still be in Bridge, you can't write to a Raw file only read from it.
Any alterations you make to the Raw file in the Raw Converter are kept in a .xmp file, also referred to as a 'sidecar' file, which is normally not shown.
If you go into Bridge and go to the View menu and select 'show hidden files' the .xmp file alongside every image will appear.
If you want to get rid of any changes you have made to the Raw file in Camera Raw you can just delete (right-click>delete) the associated .xmp file which will delete all the changes you have made, as soon as you open that Raw file up again PS will create a new .xmp file.
Chris