This is a video tutorial in the Computers & Programming category where you are going to learn how to reformat your computer. Make sure you back up all important files on a flash drive or CD. Take your operating system CD in to your CD drive and boot up your computer. When the PC comes on, it will ask you to boot from the CD. Press any key to do so. Press 'enter' when windows set up loading is completed. Then type in 1 to format the C drive. Then when the windows prompt comes up, type in "format C:" when prompted to proceed with reformatting, press Y to proceed. After the reformatting, the computer will reboot and you will have a blank C drive.