Hello and welcome to Apple Support Communities, wandafrombeavercreek.
If we understand your post correctly, you're unable to send or receive mail on your iPhone. We’d like to help.
If you're using the Mail app follow these steps:
If you can't receive email on your iPhone, iPad, or iPod touch
If you're using the Yahoo app follow the steps in this article:
If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open
Let us know if that resolves this issue for you.
Thanks for using the Apple Support Communities.