What kind of a computer is it? It might have a recovery partition on it and if it does there are tw things you can do to get a recovery disk made.
Read the manual that came with the computer
call tech support for the computer manufacturer and have them walk you through making a recovery disk..
If the computer is a HP or a Compaq fololow the instructions below:
HP and Compaq Desktop PCs - Obtaining a Recovery CD or DVD sethttp://h10025.www1.hp.com/ewfrf/wc/generic...cname=bph07143#