user92520: Assume you're Satoshi Nakamoto, completely, and that you've forgotten your private key/s. How do you prove that this is true, using the BTC blockchain? Is there a transaction you can make, or a message you can sign? Remember, you don't remember your private keys. 

user63872: 
...you've forgotten your private key/s. How do you prove that this is true

You cannot prove that you have forgotten something. How would you prove you don't have a secret backup hidden away?

Is there a transaction you can make, or a message you can sign?

No, making transactions and signing messages are both actions that require the use of your private key to complete. 

92520: <p>Assume you're Satoshi Nakamoto, completely, and that you've forgotten your private key/s. How do you prove that this is true, using the BTC blockchain? Is there a transaction you can make, or a message you can sign? Remember, you don't remember your private keys. </p>
 63872: <blockquote>
  <p>...you've forgotten your private key/s. How do you prove that this is true</p>
</blockquote>

<p>You cannot prove that you have forgotten something. How would you prove you don't have a secret backup hidden away?</p>

<blockquote>
  <p>Is there a transaction you can make, or a message you can sign?</p>
</blockquote>

<p>No, making transactions and signing messages are both actions that require the use of your private key to complete. </p>
