If the lens was extended when the camera was dropped the lens barrel is likely bent which may keep it from retracting. If it was extended and did retract, it is likely that it is jammed.

If the lens was retracted when dropped, lay the camera on a table with the lens pointed up.
See if the segments (rings) of the lens barrel are not evenly spaced. That would indicate that the gear box has jumped a tooth. Press the edges of the rings to try to reposition the lens rings. You should hear it pop if it goes back into position.

If the camera is dead, check the AA batteries and see if they are positioned correctly.
Install new alkaline batteries.

If that does nothing, it is likely the camera will need shop repairs.
Call Canon, sometimes they can offer you a rebuilt camera at an attractive price.