what kind of editors should i use and whare in JA base do i find C++ files

First, you need to download the source code. Just do a google search for jedi knight academy sdk download and you should find it. Second, you need a text editor of some sort. It sounds like you didn't go out and purchase visual studio.net so you could always use notepad that comes with your windows os. JA, like every other quake based game, uses C and not C++. All the source .c files are in the source download, so just download that and open each one with notepad..

now i want to edit the disruptor projectile in SP
when you say sorce code will this work is SP
cuz only the sorce code out is for MP right

source code for SP has never been released for both ja and jo :/, you can only modify the MP code so far.

so i cant do it than
RRRRRRRRRRRRRHHHHGG
DANG