What Is Rebuild MBR?

“Rebuild MBR” is to rebuild damaged Master Boot Record and make it correct, workable and suitable for computer to run the current Windows operating system. This function is mainly used when computer system is out of usage or runs very slowly. Sometimes, you may receive error message liking "operating system not found" or “system missing” during OS starts up. However, this does not mean that your system just runs away or been damaged; it is most likely caused by crushed Master Boot Record (MBR). In such situation, rebuild MBR is the key point. Yet, there is no such function either in Disk Management or in other Windows built in application to complete this operation. Then, what can we do?