Formatted C Drive, now CD won't work with bootdisk

My kids have an old PC that was so full of malware and viruses that I spent two days with your list of removal steps before it yielded enough for me to even format the hard drive. They were running Windows XP before I formatted the hard drive. Now I can't seem to get the CD to work, so that I can load the operating system back onto the PC. Can you offer any suggestions for resolving the problem?

 

Did you try to boot from the CD ??? if not goto bios and make your CD-rom your first boot and go from there.....

 

Yes, I've had the CD as the primary boot choice all along, but it wasn't responding, so I ended up booting off a floppy.