dell inspiron 1100 won’t boot from cd

Okay, so I want to completely restore this computer to factory settings because it has had some major problems. So I did what I was told by Dell at one point which is shut down the computer and restart it, then put in cd and hit the F12 key and “boot from cd” however when I do that, assuming the computer reads the cd I then get error messages that a file ir corrupt. So it will never reformat the h.D. or load the CD. What other options do I have to wipe the slate clean. Thank you very much in advanced.