Hello, and welcome to JustAnswer.com!My name is XXXXX XXXXX I'm here to help.
Open Safari on your iPad, and hold down the sleep button at the top of the device until the Slide to power off option appears. Then, hold down the Home button at the base of the device until it takes you back to the Home screen. Make sure you hold the Home button, don't just push it.That should do it. If what I recommended doesn't help, or if you have additional questions, please let me know and we can continue troubleshooting.
I did exactly as you directed. Still get the white screen when I try to view yahoo mail. I have even tried to be sneaky and go to different pages such as "My Yahoo" first and THEN accessing mail, but that doesn't work either.
Try manually typing in m.yahoo.com in your Safari browser, and see if it takes you to the Mobile Yahoo screen.
That brought the yahoo screen as you said. So strange - it can show me previews of my email in the layout, but when I click on the mail function or an email in the preview screen I get the stupid white screen again. I had even tried deleting my yahoo account from the Mail area on the ipad in case something had been creating conflict. Didn't help so I added it back in.