need to restore deleted partitions, system still running

[Mina Magdy]

I know this is an old thread but it comes at top result in google search
So here is how I recovered my partitions in simple steps

step 1

mina at mainpc ~ $ cat /proc/partitions |grep sda
   8        0  488385527 sda
   8        1   48837568 sda1
   8        2     104422 sda2
   8        3    2072385 sda3
   8        4          1 sda4
   8        5   20971520 sda5
   8        6  209715200 sda6
   8        7  206679833 sda7


step 2
these big number are partitions size in blocks, fdisk uses sectors
in my case a block = 2 sectors
so I started created new partitions using fdisk with
size = (size in partitions file * 2)
for example here is how I re-created my first partition


Select (default p): p
Partition number (1-4, default 1): 
Using default value 1
First sector (2048-976771054, default 2048):  <== I leave that to default
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-976771054, default 976771054):
+97675136


in my input +97675136 notice the + at the beginning (very important) also
97675136 = 48837568 * 2 where 48837568 is the number i got from /proc/p..

when u r done to make sure u did it right, try to make an extra partition
it should say "No free sectors available"

NOTE:
if you didn't get the "No free sectors available" message that
either mean u  didn't do the steps correctly or
last time you partitioned u didn't make use of your entire HD

Hope that helps