That's the way it should be.
The ????? Boss/Base options won't become available till suitable sketches have been created.
The Cut, Fillet, Pattern, etc, options won't become available till a solid has been created.
Let me get on your case about your terminology. Like many others, you say "drawing" when you don't mean a drawing at all. In this particular case, you aren't opening a new drawing, you are opening a new part. If you use the right terms, it makes it much easier for people to understand what you are doing and help you out.
As Kelvin pointed out, create a solid by extruding or revolving. Most of the buttons that once were grey will now be sunshine. :-)