Lost key for the Carrot Town door

[Stylus]

A while ago, I used the key from the secret area on the door at the start of the sliding crate puzzle just before the carrot town. Since completing the game i've returned and i've found a key near that unlocked door. I can't remember how it got there. But I went to carry the key to the carrot town door and accidentally shot at it. Now it has disappeared and the respawn button in the secret area does not respawn keys. Help!