Format the hard drive in DOS by using the "format c:" command. "C:" refers to the partition that the user wants to format. MS-DOS versions 3 and newer do not require the user to specify a partition and automatically format the system partition if the user does not enter partition data.
Type "format c:" to initiate the formatting process, and press Enter. When DOS asks for a confirmation, type "Y" and hit Enter. While the formatting takes place, make sure no errors occur. Bad sectors can appear in the case of an unexpected system shutdown during the formatting process. Once the process finishes, type "fdisk /mbr" and press Enter to return to the DOS prompt, and restart the system.
It is also possible to further customize the output of a format. Add "/q" at the end of the command to perform a quick format, "/c" to check for bad clusters while formatting and "/z:" followed by a number to set the cluster size. Any number put after "/z:" is multiplied by 512 bytes. For instance, "format c: /q /z:2" formats the C: partition quickly and with a cluster size of 1024 bytes.
A quick format only deletes the file journal of a hard disk partition. As a result, it does not scan for bad sectors and does not actually delete any data. It is possible to retrieve old files after a quick format by using a recovery program. A quick format is not as safe as a full format.