Hello sarah,
There is only one screw on the presser foot bar, see if it has come loose, check the bar to see if it has bent in the fall, you will soon know as you lift the bar, when the bar is down with the faceplate open see if the spring and stop is sitting on top of the bar, it should be, if it is not then loosen the screw where the spring is and let the spring go down then tighten the screw back up again.
Ken
drivewithken@blueyonder.co.uk, December 2008