However, if these files are missing or corrupted then OS will be unbootable - remember the famous error "NTLDR is missing. ) depending on the file system type on that partition. If so, executable code in MBR selects an active partition and passes control there, thus it can start loading proper files (COMMAND.COM, NTLDR. Partition Table exists and contains at least one active partition.Master Boot Record (MBR) exists and is safe.Clusters chain recovery for the deleted entryįor the machine to be able to start booting properly, the following conditions should apply:.