I'm assuming it's electric.

first, replace the electronic speed control (ESC)
second, put a switch between escrow and battery.
third, set up your fail safe defaults in your transmitter. Read the instructions on that as it differs from one reciever brand to another.

But, chances are, your esc is messed up from the crash so it's gotta be replaced. You also need to check the motor, make sure the shaft didn't bend from the running prop strike. The switch (about ten bucks) gives you a way to set off power between the battery and ESC quickly without fighting to disconnect the battery should you have another issue.