Failed to boot Grub Error Fedora 17

Question

I had two hard disks. One is internal, 320GB, all NTFS, where Windows 7 is installed in a ~20GB partition. The other is external, 160GB, where I have installed Fedora. Now when I had installed Fedora I completely detached my internal drive so there is no relationship between internal drive (having Windows) and external.

I had installed Fedora17 32bit on my 168GB external drive & I was loving it for about 2 weeks. However something bad happened and now whenever I boot via external drive 'Grub Error, unknown filesystem' appears and I can't proceed. I had been using following partitioning layout: (all as ext4)

/boot 300mb
/ 30gb
/opt 9gb
swap 2gb

...rest as NTFS (to be used universally)

The following application (under Windows) has the feature of even identifying Linux based filesystems but as you can see everything is corrupted.

Now I can absolutely recal that I did two things that I believe may be the source of corruption & I urgently need help in troubleshooting it.

1. First thing I did was to apply this tutorial. I know this may appear stupid to apply Ubuntu way over Fedora but I was close to solving it... After applying this tutorial I did log-off several times perfectly but didn't reboot!

2. This may well be the probable reason of corruption. As I said I had one NTFS drive so that I can use it even under my Win7...so I logged on to my win7 as always. I had to do some data transfer from my windows to that NTFS partition but I saw some folder namely ./install or something like that those may have been created by Fedora but I (being silly) just deleted them I don't know whether they were important or not but after this I shutdown my Win then booted via external drive and first time my Fedora took me to Grub selection menu but failed to start I can't recall comprehensively but it asked me to press Ctrl+D or enter root password for recovery I suppose.

I panicked (because I have installed many educational application in my Fedora) and just restarted via pressing Ctrl+Alt+Del then the final dreadful error 'Grub error Unknown filesystem`.

I booted via bootable USB the same O installed Fedora with, the following screenshot is of application 'Disks'

It doesn't recognise anything except the swap and NTFS (labelled khanz) partitions. I even can't retrieve my Maple/Matlab licences from these (as of now) — unknown filesystems?

I was told that I should have a separate /boot partition because that avoids what I am facing presently, but that didn't go well either.

Answer 1

I assume that you somehow made some typo error and you ended by losing the ext4 suberblock.

Boot from a live cdrom or liveusb and try to recover the superblock following these instructions:

1. mkefs -n /dev/sdXY
2. e2fsck -b

For you to get the proper alternate superblock you need to now how the filesystem was originally created. So if you by any change did not use the standard blocksize during the creation of the filesystem, add to step 1 the -b http://blog.mattrudge.net/2012/03/17/recovering-bad-superblock-on-ext4/

If this is indeed your problem them after the fsck you should be able to mount your filesystem normally.