I don’t know if you can if you lose your email address, but I was able to get in once by searching for my video. I then used the username on the video to get an email sent to me about changing the password. I had a few different email addresses at the time and had to go through them all to find the email from YouTube.
I don’t know what I would have done if the email address was no longer valid. I had a Verizon Server account around the same time that was deleted when I changed servers. This was a while ago and I noticed that YouTube has changed some of it polices so I don’t know for sure if it will work without the email address, but you could try.
