recovering an filesystem corruption - Linux

Sorry for using english, I'm running on a old liveCD.

When I boot my system (Ubuntu 12.04) half an hour ago, it crashed.
Only black screen with mouse pointer show up after login into lightdm.

I rebooted, get dropped into initramfs prompt. The disk keep spining up and down.
Tried mounting the filesystem, but in vain.

Now I booted from liveCD,
# dd if=rootdev bs=4k skip=1 count=1
and got:
00000000 ff a1 00 00 10 00 00 00 c0 aa bc 54 16 93 06 00 |...........T....|
00000010 0f c2 06 00 00 00 00 00 00 00 01 00 00 00 00 00 |................|
00000020 00 00 00 00 01 00 00 00 2f 75 73 72 2f 62 69 6e |......../usr/bin|
00000030 2f 6d 6c 6f 63 61 74 65 00 00 02 00 00 00 00 00 |/mlocate........|
00000040 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00000060 00 00 00 00 b4 d8 dd c6 00 00 00 00 00 00 00 00 |................|
00000070 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000080 1c 00 00 00 e0 e2 7e 84 e0 e2 7e 84 30 0d 4d 78 |......~...~.0.Mx|
00000090 67 2d 4b 51 e0 e2 7e 84 00 00 00 00 00 00 00 00 |g-KQ..~.........|
000000a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00000100 ff a1 00 00 20 00 00 00 e7 0b bb 54 67 2d 4b 51 |.... ......Tg-KQ|
00000110 67 2d 4b 51 00 00 00 00 00 00 01 00 00 00 00 00 |g-KQ............|
00000120 00 00 00 00 01 00 00 00 2f 75 73 72 2f 73 68 61 |......../usr/sha|
00000130 72 65 2f 6d 61 6e 2f 6d 61 6e 31 2f 6d 6c 6f 63 |re/man/man1/mloc|
00000140 61 74 65 2e 31 2e 67 7a 00 00 00 00 00 00 00 00 |ate.1.gz........|
00000150 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000160 00 00 00 00 b5 d8 dd c6 00 00 00 00 00 00 00 00 |................|
00000170 00 00 00 00 00 00 00 00 f1 99 77 06 00 00 00 00 |..........w.....|
00000180 1c 00 00 00 e0 e2 7e 84 e0 e2 7e 84 6c f5 69 4e |......~...~.l.iN|
00000190 67 2d 4b 51 ea e2 7e 84 38 2d c2 54 08 00 00 00 |g-KQ..~.8-.T....|
000001a0 6a 88 18 00 00 00 00 00 65 78 74 34 5f 6d 61 70 |j.......ext4_map|
000001b0 5f 62 6c 6f 63 6b 73 00 00 00 00 00 00 00 00 00 |_blocks.........|
000001c0 00 00 00 00 00 00 00 00 51 02 00 00 38 2d c2 54 |........Q...8-.T|
000001d0 08 00 00 00 51 02 00 00 73 88 18 00 00 00 00 00 |....Q...s.......|
000001e0 65 78 74 34 5f 6d 61 70 5f 62 6c 6f 63 6b 73 00 |ext4_map_blocks.|
000001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000200 ff a1 00 00 0b 00 00 00 c0 aa bc 54 67 2d 4b 51 |...........Tg-KQ|
00000210 67 2d 4b 51 00 00 00 00 00 00 01 00 00 00 00 00 |g-KQ............|
00000220 00 00 00 00 01 00 00 00 2f 62 69 6e 2f 6d 74 2d |......../bin/mt-|
00000230 67 6e 75 00 00 00 00 00 00 00 00 00 00 00 00 00 |gnu.............|

which is not at all an ext4 FS

Then I tried
# mount -t ext4 -oro,sb=163840(or 32768, etc., the common backup superblock position) /dev/sda5 /mnt
mount: wrong fs type, bad option, bad superblock on /dev/sda5
.....

smartctl -a gives some panding sectors

Then what else can I do to recover/mount my system?
And does it look like I have to replace the disk?

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