When you try to turn on the system, do you see any lights?
or when you plug it to the ac adapter, does tha ac/charging sign glows on ?
If charging doesnot glows on, probably the circuit problem somewhere. If lights goes on and respond to the power button but cannot see anything, that could be monitor
If all lights are responsive but doesnot turn anything on or doesnot responds to the power button, it could be mother board.
If it was hard drive only, the bios should be able to load ( i think , but not sure)
could be harddrive + other failures too

If your computer was on when it fell off, chances of harddrive crash is pretty high.  Otherwise, it may not be the hard drive.
So , data retrieving seems highly possible.

If it is display failure, you can connect it to the external monitor .