How do I fix my yahoo email it’s frozen

Can you access your yahoo email account on a computer (Mac or PC)? If it's okay keep on reading this answer.

Shouldn't be this case, contact yahoo support team and explain your problem.

How do you access your yahoo email account on your iPhone? Via Apple Mail app or via Yahoo app?

Should be the latter, contact yahoo support team and explain your problem.

Should be the former, go to Settings>Mail>Account, delete your yahoo account, restart your iPhone, then re-add the email account , as per these instructions:--> Add an email account to your iPhone, iPad, or iPod touch - Apple Support

Regards

Giulio