The last thing you can try is to refresh your PC. You can do this by going to the Metro settings again and then clicking on General. Here you’ll see an option to refresh your PC.
Of course, the last last resort is to reinstall Windows, but that’s not a very good choice. If you’re still having issues with Metro apps not opening in Windows 8, post a comment here and we’ll help.
"Windows 8 Tips-- Windows 8 Metro Apps ,Refresh Your PC"
Reference : online-tech-tips.com