A Master Boot Record (MBR) in your computer system is the 512 byte boot sector, that is the first sector of a partitioned data storage device such as a hard disk. MBR plays an important role in disk partitioning, system bootstrapping, and disk identity. It is the main program that is used for bootstrapping the operating system after BIOS executes the machine code instructions.

The MBR is located in the Main Boot Record area in front of the first partition. Sometimes, the first sector of the partition gets corrupted. This can happen because of various reasons such as virus infections, power fluctuations, damaged operating system, abrupt system shutdown, etc. In such situations, the system gets corrupted and fails to boot. In such cases, you should look to use a third-party partition recovery software to recover partition from its corrupt state.