That's what I was afraid of. Glad you turned it right side up. Much easier to see. A screw in that screw hole doesn't hold the frame and fork together. On your type bike it is where the cable stirrup (hanging?) that operates the brakes along with the levers is fastened. Um, I wonder if your local bike shop (aka LBS) would have a screw for that. Hard to tell. I guess you had better ask them. And if your fork is loose, it isn't because of that.