Many Apple users are experiencing an issue with their iPhones, iPods, iPads and AppleWatches suddenly rebooting after receiving a text message with a specific string of non-Latin characters due to an iOS glitch. Pranksters have been taking advantage of the glitch in iOS that shortens Arabic text in the notification preview banner on the lock screen. While mainly just an inconvenience, some users report they are unable to access their messages after their device comes back on.
Apple is working on a fix that will come in the form of a software update. In the meantime, there is a workaround you can do to avoid this problem. Disable notifications for your messaging app by going to Settings -> Notifications -> Messages -> Show on Lock Screen -> Off
If you have already fallen victim to this prank and are unable to access iMessage, visit this link for possible remedies.