Also here's a tool
https://www.youtube.com/gaia_link
Here are written recovery tricks without your email address if you don't want to watch the video above, not sure if it still works:
Recovering Your YouTube Channel Account:
Go to YouTube and log out of all Google accounts.
Go to the login page, and click the link: Can?t access your account?
In the following page, enter your Channel name and click Submit
In the next page, you will be asked for the e-mail address attached to that account. It will also include a few letters of the address as a hint. Enter the e-mail address that you set the account up with. If you can?t remember from the hint, keep trying different possibilities until you find the one that matches ? no harm is done for trying wrong ones.
Once you enter the correct e-mail, you will get a message with a link to the recovery page where you can specify a new password. You now have access to your account.