After extruding the face where i extruded from is missing this is probably something simple so i'll explain in short :

after extruding , if a delete this face(pic 1) 



you can clearly see that the face where i extruded from disappeared(pic 2) 

but i want that both faces stay there , undeleted 


basically i want to have both picture 1 face and picture 3 face when extruding
but instead i get 1 and 2 .

Thanks in advance .

Note : i used to do this 2 years ago (i can tell because i've loaded some of my models from 2014) but i can't remember how i did .
You have to hit SPACE and type "extrude only edges". 
Or in edge select mode hit ALT+E and choose "only Edges"
This way it keeps the original face in place and extrudes the edges only.

If you want to select multiple faces, you have to switch to edge select mode and only select the outer rim of the faces. 


Hit only E and extrude the edges: