How do I sign into Youtube using Yahoo Mail?

[Grogster]

I signed up for a Gmail account, which is now active, but I used to use my Yahoo Mail address and a password for Youtube to log into Youtube.

Now this won't work, and I have lost access to my YT username and all my favourites etc.

Does anyone know how I can get back into Youtube the old way?

Or even a new way would be fine, but the login refuses to accept anything other then the new gmail e-mail account as the login - that DOES work, but it creates a totally new YT user, which is not what I want - I need to log back into the original one I always used to use...
@ Zahid - I'm not prepared to believe that without lots of backup evidence. They could not delete your old Youtube account without your authorisation(provided you are not spamming etc).
Yes, my account is still active on YT, and all my videos and my favourites are still there. I just went to YT and searched for my username, and all the vids are there, but I can't login to YT as the owner of that account...
@ Ari - Thanks for the very comprehensive post. I will try that.
Refuses. Says password is incorrect. It might be - I have planted the seed of doubt now, by trying several that I think it might have been. I was always signed into YT, and never needed to enter the password. Therefore, I think I need to have YT send an email to my Yahoo email address to confirm my ID, so that I can reset the password for my original YT account, then I could link it to the new gmail address. Anyone know where I can get hold of YT people to do that?
Found a page to do that, where I can enter in my cellphone number, and they will txt me a authentication code, but although I went through this process three times, the txt never arrived on my phone. The number I entered IS correct, and it IS the one linked to the original account. As I cannot get the txt message, I cannot complete the option, and now, after a few attempts, I have been locked out of that as an option - probably as they think I am trying to hack the account - my own account, might I add... QUESTION: Does YT txt outside of the US? Perhaps it will never work. In am in New Zealand.