Can’t access Email Account (Need help Urgent)

Hi I am having trouble accessing an email It says

"That Microsoft account doesn't exist. Enter a different email address or get a new account."

I know this email exists as it is linked to my youtube account but I cant access my youtube account because I don't know the password.

I can send notifications from youtube to email but cant access it.

I really don't know what to do .

By the way I haven't logged into this email account in years but it has some important things I need to access any help will be much appreciated.

I have a feeling it may be de-activated but im not sure how I would know and if it is how to re-activate it.

I will give the email address in a private message if required as well as the youtube account.

Thanks.