A volume boot record consists of two pieces: the disk parameter block and the volume boot code.
The volume boot record is created when a partition is formatted and resides on the first sector of the partition.
A master boot record is another type of boot sector.
Repairing a Volume Boot Record
If the volume boot code becomes corrupted or configured in some incorrect way, you can repair it by writing a new copy of the boot code to the system partition.
The steps involved in writing a new volume boot code depend on what version of Windows you're using:
How To Write a New Partition Boot Sector To a Windows 7/Vista System Partition
How To Write a New Partition Boot Sector To a Windows XP System Partition

