repairing without the cd?

Hi, is there a way to use the repair option from somewhere on the hard
drive?.. my son is still having problems.. he bought the computer with
windows xp already installed.. I suggested to him that what might fix some
of his problems if he uses the repair option on the cd.. he then informed me
he doesn't have the cd..:( I think I already know the answer to this one.
but thought I would ask.. thanks Rainy

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