So a user here suggested to another about Gmail's system which allows one to add a second account from an outside provider to their Gmail inbox.
I went ahead and set up my Yahoo account with this system but the moment I laid eyes on the layout I disliked it. I deleted the connection via the settings page with which I set it up but it hasn't been broken. And my actual yahoo inbox is now showing empty.
If I understand issues correctly you transferred a Yahoo Account into your G/mail account and then deleted it, now it looks as if you have completely lost your account. You could be lucky and recover it, but this could take up to 24 hours to activate, after trying to re-establish it.....as explained in the following link:-
@Alex_Highham
My account is fine but I'd like all the emails the damn thing took from my Yahoo inbox put back. Guess that's not possible though. :P
My apologies for the description, I had misunderstood.