You need some sort of bootable environment that can restore or reinstall Windows--and you probably have one. PCs that ship with Windows all come with one of the following options.

A restore disc is a bootable CD or DVD that can restore your hard drive to the exact contents it had when the PC left the factory. In most cases the recovery disc will destroy all of your data--documents, photos, and so on--while "saving" your system. Some manufacturers don't actually ship a separate restore disc with your PC, but instead install software on the hard drive that you can use to create your own restore discs. If your PC came with a restore disc, but you can't locate it, see ""

A restore partition lies hidden on the hard drive. You access it by pressing a particular key combination at boot time. Check your documentation to learn whether you have one and how to access it. The partition does the same thing as a restore disc does.

An actual Microsoft Windows CD or DVD is the best tool of them all, but unless you bought an upgrade to a newer version of Windows, you probably don't have one.

Step 2: Gather Everything Else You Need