Why my API Key has disappeared?

There are only two explanations for an API Key "disappearing":

1. If you have not been active recently and you were using the API prior to March 7th, it's possible that your API Key(s) were purged to ensure the security of your account.
2. Otherwise, if you have chosen to disable your account, this would result in the deletion of any and all active API Keys.

You should be able to create new API Key(s) with no issues.