[Loki[D.d.G]]

Reformatting requires the use of your OS cd to do a clean install of windows. Doing so will naturally wipe your hard drive clean, so it is best to make back-ups of data files you do not want to use. There are plenty of guides online that teach you how to reformat a hard drive, step-by-step, but you may also want some assistance from a tech if you really don't know what you are doing.