To perform any operation in the mail service you need to first enter the mail by logging in. If you’re not able to do so due to some glitch, then you can get the help of the customer care and dial the assistance number to speak to a Yahoo representative or you can navigate to the help center. In addition to this, you can get the necessary assistance from the tech videos on Youube.
https://www.onlinesupportphonenumber.com/yahoo-customer-support/
https://www.onlinesupportphonenumber.com/yahoo-customer-support/