If your iPhone screen goes blank and does not respond, it could have a dead battery or it could have a more serious issue. You can try resetting the phone to see if it recovers and, if all else ...

Some iPhone owners are complaining that the Mail app has started crashing, glitching, and showing a blank screen upon loading ...

Is your iPhone (or iPad) showing a white screen ... but keep holding the other button. If your phone's screen is black, you're in DFU mode. If you see an iTunes logo, you need to start again.