What does it say in the documentation that came with the laptop?
Most laptops allow you to press a certain key on the keyboard as the laptop is booting up and that allows you to go back to factory settings.
However it does rely on the "image" being stored in a hidden area on the hard disk (which most laptops have nowadays).
If not there may be an option to create a set of recovery DVDs and this should be an option on the laptop.
It will all be explained in the laptop documention.