If your PC isn’t performing as well as it once did, and you don’t know why, you can refresh your PC without deleting any of your personal files or changing your settings.
Note
If you upgraded your PC from Windows 8 to Windows 8.1 and your PC has a Windows 8 recovery partition, refreshing your PC will restore Windows 8. You’ll need to upgrade to Windows 8.1 after the refresh has finished.
Warning
Applications you’ve installed from websites and DVDs will be removed. Applications that came with your PC and apps you’ve installed from the Windows Store will be reinstalled. Windows puts a list of removed applications on your desktop after refreshing your PC.
Taken from the refresh details page