Software & Apps Windows How to Format C From a System Repair Disc Share Pin Email Print Command Prompt in System Recovery (Windows 7 System Repair Disc). Tim Fisher Windows The Ultimate Laptop Buying Guide By Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated June 24, 2019 One way to format C is by using the format command from the Command Prompt, accessible from outside of Windows via a System Repair Disc. A System Repair Disc can be created from any working Windows 7 computer but can be used to format C no matter what operating system is on the C drive. Follow these steps to format C drive using a System Repair Disc: A System Repair Disc does not install Windows 7 and you will not need a product key to use a System Repair Disc. Difficulty: Easy It could take several minutes up to hours to format C using a System Repair Disc How to Format C From a System Repair Disc Create a System Repair Disc in Windows 7. As we mentioned above, you'll need access to a Windows 7 computer to create a System Repair Disc. However, it need not be your Windows 7 computer. If you don't have a working, Windows 7 based PC then find a friend that does and create a System Repair Disc from his or her computer. If you can't find a way to create a System Repair Disc then you won't be able to format C this way. If you have a Windows Vista or Windows 7 Setup DVD, you can boot to it instead of creating a System Repair Disc. The directions from this point forward using a setup disc will be pretty much the same. Boot to the System Repair Disc. Watch for the Press any key to boot from CD or DVD... message after your computer turns on, and be sure to do that. If you don't see this message but instead see the Windows is loading files... message, that's fine, too. Wait for the Windows is loading files... screen. When it's over, you should see a System Recovery Options box. Change any language or keyboard input methods you need to and then click Next >. Don't worry about the "loading files" message... nothing is being installed anywhere on your computer. System Recovery Options is starting, that's all. A little dialog box appears next that says "Searching for Windows installations...". After several seconds, it will disappear and you'll be taken to a System Recovery Options window with two options. Choose Use recovery tools that can help fix problems starting Windows. Select an operating system to repair. and then click Next >. Your operating system may or may not be listed. If you're using another operating system like Windows XP or Linux, nothing will show up here - and that's OK. You do not need a compatible operating system on this computer to format C this way. Click on Command Prompt from the System Recovery Options screen. This is a fully functional Command Prompt and contains all of the commands you'd expect to be available from the Command Prompt in an installed version of Windows 7. At the prompt, type the following, followed by Enter: format c: /fs:NTFS The format command used in this way will format C with the NTFS file system, which is the recommended file system for most Windows installations. The drive that Windows is stored on, which is usually C, may in fact not be identified as the C drive from the Command Prompt from a System Repair Disc or a Setup Disc. For example, in most Windows 7 installations, the C drive is reported as the D drive here. Be sure you're formatting the correct drive! If you'd like to format C using a different file system or in a different way, you can read more about the format command here: Format Command Details. Enter the volume label of the drive you're formatting when asked and then press Enter. The volume label is not case sensitive. Enter current volume label for drive C: If you don't know the volume label, cancel the format using Ctrl+C and then see How to Find the Volume Label of a Drive From the Command Prompt. If the C drive doesn't have a label, which is often the case, you obviously won't be asked to enter it. So if you don't see this message it just means that the C drive doesn't have a name, which is fine. Just move on to Step 8. Type Y and then press Enter when prompted with the following warning: WARNING, ALL DATA ON NON-REMOVABLE DISK DRIVE C: WILL BE LOST! Proceed with Format (Y/N)? Take this seriously! You can not undo a format! Be very sure that you want to format C, which will remove your operating system and prevent your computer from starting until you install a new one. Also, as we mentioned in Step 6, make sure the C drive really is the drive you think it is. Wait while the format of your C drive completes. Formatting a drive of any size will take some time; formatting a large drive may take a very long time. If your C drive happens to be very large, don't worry if the percent completed doesn't even reach 1 percent for several seconds or even several minutes. After the format, you'll be prompted to enter a Volume label. Type a name for the drive, or don't, and then press Enter. Wait while Creating file system structures is displayed on the screen. Once the prompt returns, you can remove the System Repair Disc and turn off your computer. There is no need to exit the Command Prompt or do anything else in System Recovery. That's it! You just formatted your C drive. As you should have understood from the beginning, you remove your entire operating system when you format C. This means that when you restart your computer and attempt to boot from your hard drive, it will not work because there's no longer anything there to load. What you'll get instead is a BOOTMGR is missing or an NTLDR is missing error message, meaning there was no operating system found. How to Format C Without a System Repair Disc We have a list of several other ways you can format the C drive if you don't have a Windows 7 System Repair Disc or if you'd just rather go a different route. For example, if you're giving away the hard drive or entire computer, you can wipe the drive with a data destruction program to make sure that it's really hard, or even close to impossible, for anyone to recover your personal files.