I can not log in to Yahoo[for emails] as They keep rejecting my password.Ido not remember changing it to something different

This is a international question and answer site, we are not connected to Yahoo. You will have to do a reset password from Yahoo. Answer the security questions you present.

Do one thing. Fill the email id. Then, you will have to fill the password, which you do not remember, any longer (as it seems) or it got hacked.

R-E-L-A-X

There is an option, where you will be asked to fill in your mobile number, and if you have two or more mobile contacts, here is satisfactory solution. They provide last few numerics. Fill the mobile number and you will receive and alpha-numeric code. Fill that code in the space, left black by YAHOO. Your email id will generate a new password, which you can change at will.

If it helps, tell me, if not, I shall give you alternative solution.
Do not worry, your problem is solve-able!