@calabrese ,Stephen, The camera lens has a very small delicate set of gears inside which control the lens movement and when the camera was dropped the meshing off these gears were probably thrown out of alignment. It is not recommended for the inexperienced to try a repair on a lens. Best to pop into a good local camera shop and have them take a look and estimate repair.
What you can do is check for any dust/debri/sand etc., that may be stuck between the lens barrel and where it retracts into camera and use something thin(small strip of paper) and go all the way around the lens barrel and pick dust/debri out, to see if it was being jammed by dust/debri/etc.
Good luck. I hope this helped you out, if so let me know by pressing the helpful button.