Many people format the HDD with use of command prompt, and other tools but before format the drive we need to know that what the actual condition of the HDD.I am an computer engineer and I experienced it that which type of format will be needed for HDD. Many people said that FAT32 format is good or NTFS format is good, no that is the only partition type nothing else . IN actual Hard disk stored data in sectors and if there is any kind of bad sectors in it that is cause of problem in it. So during formatting bad sectors need to be removed or repaired . For this we can use windows 98 CD to format the HDD this is the old way but secure and great another one is use Low Level format tool that is freely available on the internet and and it format low level sectors of HDD that is great thing. I have given link of that software use it https://downloadsafe.org/file/a6d85P