At first please make sure you dont have any cd/dvd in your drive. Then if you want to restore your system to factory default then you can do it by follwoing few simple steps.
Turn on your laptop and keep pressing ALT + F10 key until you see a message on screen Window is loading files...once you see this message sit back and wait for instructions to follow and choose restore system to factory default when option appears.
I hope this will helps you.
Imran Khan From London