|Most laptops without CD drives have an inbuilt restore feature, run from a hidden partition on the hard disk.|
As you did not give the make and model of the computer then your best bet is to go to the manufacturers of your laptop and see if there is such a procedure. There might be a user manual around that covers this if you google around.
If not, take the advice given in #1.
Note that this could be a hardware fault - make sure your case vents are clear.
Always pop back and let us know the outcome - thanks