This is the step that's a little scary, because of its finality. Once you reformat a drive, for most practical purposes you wipe clean the remaining traces of data, the software programs and the operating system. On the other hand, that isn't necessarily a bad thing, because you're also going to undo any software problems and destroy any malware that's infected the PC. So eventually, once you reinstall a new copy of the operating system, it may run even better than before [source: Phelps].
The first step is to repartition your hard drive. You can do this by opening the Windows Control Panel and clicking System and Security, followed by Administrative Tools, and double-clicking on Computer Management. You'll probably have to provide the password for your main user account, the one with administrator privileges that allows you to alter the computer's settings. Once you do then go to the Storage menu, and click Disk Management and then New Simple Volume. That will bring up a wizard program that will guide you through the rest of the process [source: Microsoft]. The process could take a few hours to complete.