How to Troubleshoot, Repair, or Restore Windows 8
Windows 8 comes with a number of tools for system maintenance and repair. Here’s a quick way to access many of these tools and to troubleshoot problems.
Open the Charms bar. One way is with the keyboard shortcut Winkey+C
Click “Settings”
Click “Power”
In the menu that opens, Click “Restart” while holding down the left Shift key
The screen shown below will open
Choose “Troubleshoot”
The screen shown next will open. Among the choices are refreshing or resetting or a number of advanced options.
Choose the option you wish to use
Advanced options includes a number of choices as shown in the figure below
Read How To Reset Your Windows 8 Computer
More information from Microsoft: http://windows.microsoft.com/en-us/windows-8/restore-refresh-reset-pc