2003 honda odyssey key wont turn in my ignition

Hello, your ignition cylinder could be worn out, or your key could be. I would start by using a different key and seeing if it helps any. Also, you an have a dealership cut a new key from a key code that should be an "original fit" - this can at least determine if the lock or key is the culprit. Keep in mind: any new keys must be programmed with each existing key.