Stopped receiving yahoo email on iPad but still working on iPhone. Have tried deleting and reinstating yahoo acct with no success

Yahoo mail acct stopped incoming mail on IPad 3, but mail still being received on iPhone 4s. Went to Apple genuis. deleted yahoo acct and reistated. No success

They opened a second yahoo mail acct, but original one on iPad still not working and I have lost two of my mail folders, but they are still available from my phone. Was told by genius to wait and see if it corrected. Has not.