ENGL145 AM - MA, He (Martin) - Week 2 2/2

Last weekend, my computer did not work, and I decided to fix it. I found a store which could fix it  in Crystal mall. There was only one worker in that store. He also is the boss. When I told him what the problem it is, He said that I need put my computer here for one day because he need lots of time to fix the problem. Next day, when I got my computer from him, I found there was a screw disappeared in my computer, and computer worked so slow. I never touch the screw before. I guess he might exchange something from my computer but there is no evidence. What should I do…...