Q: Icloud and yahoo mails

To restore your iCloud mail account, go to Settings>iCloud and check Mail.  If it's already checked, uncheck it, then check it again in a few seconds.

To restore you Yahoo account, go to Settings>Mail,Contacts,Calendars>Add Account>Yahoo.  If is already set up, tap the account and delete it, then set it up again.

Can you elaborate?  What happens when you try?  Error messages?  Symptoms?

Some things you can try include:

1. Force close the Mail application (from the home screen, double-tap the home button, locate Mail in the list at the bottom, then swipe up on the image above the app icon to close it).
2. Reset your phone by holding the power and home buttons at the same time until you see the Apple logo, then release.
3. Restore your phone.

Try adding your mail accounts again after each one.

You're welcome.  Glad it's fixed.