Ok, I want to upgrade my favorite 7 speed fuji hybrid to a 9 speed. what components do i need to get in order to upgrade? I have few spare parts like shimano lx 9 speed shifter, do i need new cranks as well as front & rear derailleurs and rear hub?
More gears is not an upgrade. It's just more gears.
You have the shifter, so now you need a cassette, rear derailleur, and at least a new freehub body to replace the old one on your rear hub. You'll likely have to respace your rear axle and redish your rear wheel after switching over.
The old cranks, chainrings, and front derailleur will probably work fine.
my bike is unusable since my freewheel is broken and my grip twisters are also falling apart. i will be doing this project to get it up and running again since it is my favorite. i will have to use my other hybrid which is 27 speed and want to make the spares a bit more compatible