The way in which you prepare hard drive for use is formatting. The file system of the hard drive is structured to store data and can be set to any files system such as FAT 16, FAT 32, ExtFAT, NTFS 4 or NTFS 5 in case of Windows XP, Vista or Windows 7 or HFS + or HFSX if it is a Mac operating system.
Several problems occur while or after formatting a hard disk, some of them are –
If the hard disk is physically damaged, which means that whatever data is stored on the damaged sections would get either corrupted or inaccessible. In general, these damaged / corrupted sections are called as bad sectors, and formatting, reformatting the hard disk drive to get rid of these sectors could definitely end in problem and result in data loss.
If you are trying to re-partition a hard disk using some third partitioning utility then they may result in partitioning errors and end up losing valuable data present on the disk.
If the hard disk is corrupted by virus, the boot sector may get corrupted by virus and the operating system crashes then you will not be able to access the data. In such a case, you format the hard drive.
Some times even reformatting the hard disk drive makes the data irrecoverable. Reformatting actually involves file system conversion i.e. FAT to NTFS. This also results in data loss if you do not have a proper backup of data.
However, in any of the above cases, data recovery after formatting hard disk is possible as only the partition table is erased so the actual data still resides on the drive, provided, the disk space has not been overwritten by new files.
In order to recover data after format, use formatted data recovery software that is capable of recovering lost / deleted data from both formatted, re-formatted, repartitioned hard drives in PC or laptop.