Try Resetting the Board
After a drop, there are any number of things that can be wrong, but since getting power is the very first step, see if you can Reset your laptop.
To do this, remove the battery and AC Adapter cord, and press and hold the power button for 30 seconds. Then, without replacing the battery try plugging in your AC Adapter to see if you get any love. If that doesn't work, remove the AC adapter, reset the board again, and this time hold the power button down as you plug in the AC Adapter cord. If you still don't get any lights, you could try removing your memory, reset the board, replace the memory, plug in the AC Adapter, and try one more time. If all of this fails, follow the advice of the other guys and get an external hard drive enclosure so you can retrieve your data from the hard drive.
I work on laptops for a living. The cost to replace the motherboard will likely be around $180-200 for the labor plus the cost of the board which may be anywhere from $100 - $250.