Yahoo messages show up 'blank' whenever I click on hem to read/reply to messages

I had an international flight yesterday and I'm afraid that I might have accidentally changed something in settings is all that I can figure out that has happened. I've gone to settings to see if I can see anything that needs to be changed but I give up and I don't know what to do.I can get into yahoo, I can see the inbox showing the list of mail (old and new messages), and I can even read some of the messages on the far left side of the screen where the list of who the message is from.I've only owned my new iPad for a little over two months and I love it. This is the first problem that I have had with it too. I really enjoyed being able to read my emails and send them while away from my upstairs computer. I had especially looked forward to this as I recover from my recent knee surgery as I am still having difficulty climbing stairs.I have the 64 wifi only newest model.