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Partition is deleted or Partition Table is damaged

Consider the situations which cause a computer to hang up while booting or hang up due to data loss.

1. What will happen if no partition has been set to the Active state (Boot Indicator=0x80)?

2. What will happen if the partition has been set to an Active state (Boot Indicator=0x80) but there are no system files on that partition?

3. What will happen if a partition entry has been deleted?

If it has been deleted, the next two partitions will move one line up in the partition table.

   Physical Sector: Cyl 0, Side 0, Sector 1
   0000001B0                                              80 00   ..............€.
   0000001C0   41 3F 06 FE 7F 64 7F 32  4E 00 A6 50 09 00 00 00   A?.?d2N.¦P....
   0000001D0   41 65 0F FE BF 4A 25 83  57 00 66 61 38 00 00 00   Ae.??J%?W.fa8...
   0000001E0   00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
   0000001F0   00 00 00 00 00 00 00 00  00 00 00 00 00 00 55 AA   ..............U?

When trying to boot now, the previous second (FAT) partition becomes the first and the loader will try to boot from it. And if it's not a system partition, the same error messages will appear.

4. What will happen if a partition entry has been damaged?

How can recovery software help you in the above-mentioned scenarios?

1. Discover and suggest which partition is to be set as active (FDISK also does this).
2. Perform a disk scan of the free space to look for a partition boot sector or remnants of deleted partition information in order to try to reconstruct the Partition Table entry for the deleted partition.
3. Perform disk scan on all space to look for partition boot sector or remnants of deleted partition information in order to try to reconstruct the Partition Table entry for the deleted partition.

Why is the partition boot sector so important?

It contains all the necessary information about the partition so that if recovery software finds it, it can reconstruct the partition entry in the Partition Table. (see Partition Boot Sector topic for details).

What would happen if a partition entry had been deleted then recreated with other parameters and re-formatted?

In this case, a new partition would exist instead of the original one. Everything would work properly with the exception that you could not go back to the original partition if important data is still there. If you've created a MBR, a Partition Table, or a Volume Sectors backup beforehand (as can be done with Active@ Partition Recovery and Active@ UNERASER for example), you can virtually restore it and look for your data (if it has not yet been overwritten by new data).

Some advanced recovery tools also have an ability to scan disk surfaces and try to reconstruct previously deleted partition information from the pieces of left over information (i.e. perform virtual partition recovery). However it is not guaranteed that you can recover something.