IPHONE WONT UPDATE EMAIL

Question

This morning I noticed that my btinternet.com emails had not updated on my iPhone although they had on iPad and iMac.
I tried powering off and on again, no solution.
Next I deleted the email account and then reinstalled it. Again, no solution and all emails which were in the various files within the account have disappeared but just on the iPhone.
My IMAP account info and incoming mail server settings on iPad and iPhone are identical and my wife's btinternet.com email account on the iPhone continues to work.
Although the files within my account have returned on the iPhone it states at the bottom of the screen that the Inbox was last updated on Saturday (today is Monday).
Any ideas???

Answer 1

Try this fix.
-->>you'll need a computer to log in to you yahoo! mail.
-->>after logging in with you username and password (computer) on the top right you'll see "Hello (your name)" CLICK ON IT
-->>on the left panel you'll see "account security" CLICK ON IT
-->>check iF you have  "Two-step verification  Additional security." TURNED ON
HERE'S THE PART TO FIX:
if you switch it OFF you can set up your yahoo mail on apple device with no prob.
if you switch it ON yahoo will generate a ONE TIME PASSWORD for your device set up. (this adds additional security to your phone)
*I highly recommend you do the ON option
to set it ON:
-->> switch the ON for Two-step verification/
-->>have a nickname for your device ex "mike iphone5"
-->>click "generate password"
-->>a long password of random letters will pop (this password will be the password when you set up your email on your ios device)
*it is to be used one time only.
-->>go to your device set email as usual.. then for the password use the long password yahoo provided.
THAT'S IT! HOPE IT HELP!
!!!! DON'T FORGET TO CLICK THE START I THIS HELPED YOU TO HELP OTHER USERS TOO.