How to restore your computer back to factory preloadedsoftware

If you would like to restore your computer back to factory preloaded
software, you may choose either option below to proceed.

(!) Make sure that the AC adaptor is connected during whole restoring
process.
(!) When you reinstall the Windows operating system, the hard disk
may be reformatted and all data may be lost, so it is recommended to
backup all your files and settings before restoring.
Do not back up files to the same hard disk that Windows is installed on.
For example, do not back up files to a recovery partition. You can back
up to another drive or DVD.
Option I:
1) In the Settings charm, click Change PC settings.
2) Click Update & recovery under PC settings.
3) Click Recovery tab.
4) Click Get started under Remove everything and reinstall Windows
5) Follow the on-screen instructions to finish the recovery.
Option II:
1) Insert the recovery media (DVD or USB flash memory) which was
made by TOSHIBA Recovery Media
Creator before updating to Windows 8.1.
2) In the Settings charm, click Power and then select Restart.
3) Hold down F12 key and then release this key one second after the
computer is power on.
4) Use up and down cursor keys to select the recovery media device,
then press the ENTER key.
5) Follow the on-screen instructions to finish the recovery.