Hard drive won't boot?

Lost Partitions?

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  Trouble-shooting Windows XP/2000 Startup Problems

Message Source Most Likely Cause Best Recovery Method
"Operating system not found" or similar wording BIOS Corrupted Master Boot Record. Specifically, the AA55h boot sector signature in the last 2 bytes of the MBR was not found. Follow these instructions to rebuild partition table and restore Master Boot Record.
None - system hangs on startup with blinking cursor on blank screen Master Boot Record or Partition boot sector 1. Illegal byte was found in the partition table's "Active" field. The partition table is corrupt. In this case the hang is deliberate behavior of the MBR's boot loader.

2. Can also result from corruption in the boot loader code of the MBR or partition boot sector, or problems with the $Boot metadata file or Master File Table on NTFS partitons.

 Evaluate with BootMaster. Rebuild Master Boot Record or restore the active partition boot sector as appropriate.
"No ROM BASIC" Master Boot Record If no active partition defined in the boot HDD's master partition table, the standard MS MBR's loader code issues an interrupt 18, which calls the ROM BASIC. Since modern computers do not have ROM BASIC, this message is usually displayed. FDISK can be used to set a primary partition to "Active." However, a better approach is a more thorough investigation of the partition table with BootMaster, since the actual problem may be more complex.
"Invalid partition table" Master Boot Record The master partition table has more than one partition marked "active." Evaluate with BootMaster. In most cases this problem can be repaired with the "Toggle Active" function.
"Error Loading Operating System" Master Boot Record An error was returned from the BIOS when boot loader attempted to read the active partition's boot sector into memory. In many cases this will be due to a "soft" ECC error and can be repaired by rewriting the boot sector with BootMaster's boot sector recovery function.
"Missing Operating System" Master Boot Record The active partition boot sector's AA55h signature was not found. Use BootMaster's boot sector recovery function.