Peter Boiter Woods
If you refer to another account:
1. After 12 months of inactivity, the account is deleted. The same if you were suspended.
2. You are on a mobile and need to be in desktop mode.
3. You need to reset your password. The instructions are found in the Yahoo Help pages (referenced) and 10000s of previously asked questions.
https://help.yahoo.com/kb/answers/recover-reset-yahoo-password-sln27051.html
Sharon
This is how to recover your account if you have password/sign in problems: https://help.yahoo.com/kb/SLN2824.html