i heard metal to metal contact after i drove over a speed bump today. it kept clunking the entire way home and i put it on my jacks found that one of the screw is missing on my shock. i think the pressure in the shock is gone because i can easily move the wheel up and down. is this a simple fix or i have to take it off and service it at bilstein.

 

That's where the shaft the shock connects to the casing. That corner currently has no shock, which is a very bad thing on a car with struts, to say the least. Drive gently - if at all - to a place that can pull the strut apart and fix it or replace it.

It's simple if you've done it before. Don't do it unless you or a helper has done this before.