If you have had your system crash and need to start from scratch, you may need to reformat your computer. Reformatting your computer will erase everything that is currently on your hard drive. You will not be able to retrieve any information from your hard disk after performing a reformat. However, this may be the only way eliminate a virus from your system after a virus infection, or you may want to reformat before you give away or sell your computer so your personal data is not on it.

Before you reformat, you should make sure that there is nothing left on your system that you want to back up. After a reformat is complete, you will not be able to find or use any information that previously existed on your computer. Your hard disk will be in a blank state.
You will need to start from the completely empty system and reload everything on the computer, starting with the operating system and then loading every program that you use. Most private users don’t bother with the hassle of backing up important files and documents on a regular basis, but it essential to do this before reformatting.
If you are going to have to reformat your computer, you should search through all the programs that you commonly use and backup any files that you have used, modified or created. Even if a virus has infected the computer, you can often recover the original files after a reformat by using a virus protection program. After reformatting your computer, you can check each file you are replacing with the virus protection program to ensure that they are virus free.
Over the life of a computer, many different pieces of software are loaded and used. Each of these pieces of software has installation files that load the application onto the computer. You will need to locate each of the disks for all software that you have installed on the computer since you started using it and make sure you have removed and backed up the installation files.
In addition, it is important that you have recorded any serial number or activation code that is required for your legal use of the software. If you have lost this information, contact the seller and have them either send you the information or tell you how to find it on your system.
Most computers come with a CD driver disk that will aid you in restoring your system in the event of a crash. Make sure you have this CD available for the rebuilding of your system after the reformatting. You should also make sure that you have all the updated drivers for your hardware. These can normally be found on the website of the manufacturer of your computer. Locate all these new drivers and download them to floppies, memory sticks or CDs for use later.
You are now ready to reformat your computer. Begin by taking the CD with your operating system and placing it in the CD drive. Turn the computer off and then back on. As the computer starts up, you will be asked if you want to start from the CD drive. Select yes and it will begin loading the operating system installation program. Once the installation program begins, it asks the operator if you wish to install a new copy of the operating system or restore a previous copy. You will want to select the new operating system.
The installation program will warn you that you will lose all data and files on the hard disk if you continue and ask if you are you sure you want to continue. This is what you want if your backup is complete, so select continue. The program will ask which hard disk you where you want to install the operating system. Select the main partition of the main hard disk from the list shown and select continue.
The installation will first erase your hard disk, then reformat the partition and finally, reload the operating system onto your computer. Answer all the questions pertaining to location, time, date and other personal information the program prompts you for during the reformatting and loading of the operating system. When the program finishes it will restart the computer with a fresh and clean operating system.
Your final task will now be to load all your application software back onto the hard disk and restore all your backed up files. Remember to check your backups for virus infections or you will be right back where you started.