Lost linked account, msgs being forwarded from linked account

For the past few months, I linked an old hotmail account to a new account because I haven't been able to sign into that account for months now.  The messages from the old account were being forwarded to the new account (and they still are, as I sent a test email to see if it would forward to the new account).  I've been able to switch between accounts by clicking under my name on the Outlook home screen.  Now, my old linked account is no longer showing up in the drop down menu and I can't access it to see all the old emails that have been saved.  I went into Settings to see if the address was linked to the new account still and nothing shows up, like I never did it.  If anyone can help, that would be much appreciated