The partition is there but its filesystem is unknown. The filesystem must be ext3 or ext2, more likely ext3.
See attached screenshot.
Code:
mount: wrong fs type, bad option, bad superblock on /dev/sda3,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
dmesg | tail
VFS: Can't find ext3 filesystem on dev sda3.
VFS: Can't find an ext2 filesystem on dev sda3.
fdisk /dev/sda3 -l
Disk /dev/sda3: 51.6 GB, 51621857280 bytes
255 heads, 63 sectors/track, 6276 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/sda3 doesn't contain a valid partition table
I tried TestDisk but it suggests very different partition table.
I'm not sure that the problem is in the partition table, because partitions look good and another partitions run well. The problem is only for sda3, probably it's filesystem.
What else I can try before trying to find files using PhotoRec?
My goal is to recover the filesystem, not only separate files because partition is used on production server.
The full story: My old PATA drive has 160 GB and I upgraded the system with new 1 TB SATA drive. Using dd I copied whole old drive to the new one. But the problem is not only on the new drive but also on the old. Therefore we cannot blame the copying (dd) for the situation, I think.