Email on iPhone

I use Yahoo for email and accessed it through my iPhone mail app. I had to change my password for the account and did so through the Yahoo website on my iMac. Now i no longer receive email on my phone. When I try to check my emil's on my iPhone, it tells me there is an error. I go to Settings>Mail>Accounts and the accounts are grayed out and I cannot tap on it in order to change the password. Any idea on how to fix?

Thanks!