If the screen is cracked it's entirely possible that the screen is totally non- functional, so you have no obvious way of telling if its on or off. One way that you can try to determine whether the tablet is functioning is to use another computer to connect to your wifi router, and see whether it has tried to to connect to the router since you dropped it.
If you're unable or unwilling to do that you have two alternatives, either replace the tablet or try to replace the screen. This isn't rocket science.