Can a Full Format make The HDD unusable?Not as long as the hard drive is working properly to begin with.I just thought I"d add a comment to be perfectly clear on this subject.  A full formatting not affect the physical condition and MECHANICAL FUNCTIONING of the hard drive but it will erase the hard drive and the drive will need installation of an operating system if it is going to be used as the PRIMARY hard drive for a computer system.  If it is merely going to be used as a storage device, such as a secondary internal drive or an external drive, then no operating system is needed on it; in other words, the operating system would exist on another drive. More information about hard drive formats is found outside of the windows knowledge base. Linux users sometimes get involved with rare formats that are not compatible with Windows. GPART is a Linux utility that gets involved.
https://en.wikipedia.org/wiki/Gpart
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gpart TRIES to guess partitions from any device that can be partitioned, even a file. If the primary partition table has been lost, overwritten or destroyed the partitions still exist on the media but the operating system cannot access them.
gpart ignores the primary partition table and scans the disk (or disk image file) sector after sector for several filesystem/partition types. It does so by "ASKING" filesystem recognition modules if they think a given sequence of sectors resembles the beginning of a filesystem or partition type.