HI! My Yahoo Mail Inbox has disappeared as well. I got a pop-up from Yahoo asking me to enter my password which happens every so often. After that I realized it wasn't the normal request to verify my password every 2 weeks, but a Yahoo request. After I did that my Yahoo Inbox in my IOS Mail app is gone. The Sent, the Spam, the Trash mail is all there. I then noticed that this is happening not just on my iPhone but both iPad Minis as well. I've rebooted, I've deleted and re-addded the accounts and no luck. It just says "No Mail". I can access the Yahoo mail on the laptop and in the Yahoo app on my idevices. I've updated to IOS 9.2.1. on 2 of the 3 devices. I got another request to verify the password on one of the iPad Minis for my daughter's Yahoo address which is connected to mine and also on all three devices. I did Cancel for the request and I was able to get my email briefly on that device. However, once I turned it off and back on it is gone. I spoke with Apple at length and they said it was a Yahoo problem. I can't locate an answer on Yahoo Help (which is crap) or a real person. Anybody got any ideas? Have I been hacked or just a glitch from Yahoo?