What is the model of your laptop?
first thing is to update your drivers and bios.. give your lapto
details can find the link for the driver
second: this can be a loose hard drive cable or connection.. so mak
sure that its well plugged.
run windows key finder and find the key of your OS on your compute
'Magical Jelly Bean Software - Magical Jelly Bean Keyfinder v2.0.1
(
http://www.magicaljellybean.com/keyfinder/
--
ashvi

Just chill
-pls post your feedback on my reputation, would be of great help t
fine tune and provide better support..-