Hi Shanks214,
Thanks for coming to Apple Support Communities for help today. As we understand, you changed your Yahoo email password and now you don't receive email through your iOS Mail app.
Have a look at this page: If you can't receive email on your iPhone, iPad, or iPod touch. Try following the instructions at the end of the page:
"Remove your email account and set it up again
- On your computer, sign in to your email provider’s website. Make sure that all of your email is there or make sure that your email is saved somewhere other than your device.
- On your device, go to Settings > Mail, then tap Accounts.
- Tap the email account that you want to remove.
- Tap Delete Account.
- Add your account again
Have a fantastic day!