When I go to my yahoo email, the part where you type in the message does not show up. How can it be fixed?

I can't reply to an email or compose an email because of this problem. So right now my account is not worth using.

When I go to my yahoo email, the part where you type in the message does not show up. How can it be fixed?
Yahoo Customer Service


Phone: 1-866-562-7219


Yahoooooooooooooooo