Let’s check the username and password carefully. I understand you know your password. But It might possible, you are not typing it correctly.
As we all know, Passwords are always case sensitive. when you are typing the password your yahoo account.
It might possible, the Caps lock is on. That’s why you are going through such kind of problem.
So type the password carefully.
let’s open the notepad and type your password there. now copy your password and paste it into yahoo login page.
If this password will not work for you. you can go ahead and reset the password.
This process will resolve the can’t sign into yahoo mail problem.