Basically I recently built my computer and installed windows 8 on it. And being stupid I forgot to change the windows update settings to notify me to install updates. Randomly when I turned on my computer one time, my metro screen was completely blank. I don't have any apps or even a desktop icon. To get to my desktop I have to type something in like "device manager" and click it and it will bring me to the desktop where everything works fine. I think the problem was caused by a windows update but I'm not entirely sure. I have no idea whats wrong. http://imgur.com/9HN7ERs
Theres a screenshot of my metro screen just in case.
If you think it was an update, uninstall it. Winkey plus 'X', choose Control Panel ad Uninstall a Program. Top left screen 'View Installed Updates'
Failing that try refreshing your Windows. Normally you could type 'Refresh' at the Start Screen, but that may not be available. In that case Restart your PC whist holding down the Shift Key and this will give you access to the Troubleshooting Menu where you could choose Refresh your PC