Below are instructions for manually recovering a deleted partition table. There are utilities such as gpart or TestDisk which can make this task considerably easier. If you are reading this, however, because you have run out of luck, this is what you will have to do:
Make a partition that is at least as big as your first partition was. You can make it larger than the original partition by any amount. If you underestimate, there will be much wailing and gnashing of teeth.
Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 1 First cylinder (1-23361, default 1): <RETURN> Using default value 1 Last cylinder or +size or +sizeM or +sizeK (1-22800, default 22800): 13032 Command (m for help): w
Run dumpe2fs on the first partition and grep out the block count.
% dumpe2fs /dev/sda1 | grep "Block count:" Block count: 41270953
Remove the partition you just created
Command (m for help): d Partition number (1-4): 1
Make a new partition with the exact size you got from the block count. Since you cannot enter block size in fdisk, you need to figure out how many cylinders to request. Here is the formula:
(number of needed cylinders) = (number of blocks) / (block size) (block size) = (unit size) / 1024 (unit size) = (number of heads) * (number of sectors/cylinder) * (number of bytes/sector)
Consider the following example, where a hard drive has been partitioned into four primary partitions of 1, 2, 4, and 8 cylinders.
disk /dev/sda: 16 heads, 63 sectors, 23361 cylinders Units = cylinders of 1008 * 512 bytes Device Boot Start End Blocks Id System /dev/sda1 1 2 976+ 83 Linux /dev/sda2 3 5 1512 83 Linux /dev/sda3 6 10 2520 83 Linux /dev/sda4 11 19 4536 83 Linux
Run e2fsck on it to verify that you can read the new partition.
Repeat Steps 1-5 on remaining partitions.
Credit goes to: Mike Vevea, jedi sys admin, for providing the basic strategy.