Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I presume that your computer was set up to log in to your Yahoo! Mail email account automatically. So you will need to 'recover your password', a procedure that is common enough for email users.
Open a web browser on your computer. Go to this address:
and then enter your email account name there, in the 'username' space.
Then enter anything in the 'password' space, and submit that. It should be refused. That's normal enough - the wrong password ***** the username will be refused. Then, you should click on the 'Forgot password?' or similarly named link next to the Username: and the Password: entry spaces, and follow the procedure there for recovering your password.
Note: if you are prompted for an email address to email the new password ***** (or anything similar) do not enter your email address that you are trying to recover... you would need to enter an email address that you still *do* have access to.