The following two kinds of situations are divided:
1, if Windows 8 can start, select Metro Control Panel application, click the "General" select "Restore the computer without affecting your files" option to reinstall Windows and retain the data, if you choose the "Initialize the computer and restart" option, Then you can restore Windows and delete your data and applications at the same time.
Choose More computer settings
Select General, and choose the repair option as needed.
2. If Windows 8 fails to start, then you can reinstall or reset your computer by using the original installation CD, selecting the Language and keyboard, clicking "Repair your Computer" and selecting "Troubleshoot".
Click the advanced option to see a tool or system image file that restores windows from a previous restore point and an automatic repair option to troubleshoot common startup problems in Windows.