重新安装Windows 7后重新安装grub后无法挂载/ home /分区

我已经在其指定的分区上重新安装了Windows 7，并且像往常一样，它用自己的东西覆盖了MBR，因此，无法启动到我的ubuntu 12.04分区。

我按照本教程的步骤进行，一切进展顺利。

之后，在我的ubuntu 12.04系统上启动时，我收到一条错误消息，告诉我在挂载/ home /时出错。我选择忽略该错误，并且引导成功地继续进行直到登录屏幕。尝试登录我的帐户时，输入密码后没有任何反应。

我打开了一个终端，看到里面没有任何东西的虚拟/ home /。

这是我的磁盘的外观：

# fdisk -l
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical) : 512 bytes / 512 bytes
I/O size (minimum/optimal) : 512 bytes / 512 bytes
Disk identifier: 0x000913aa

   Device Boot      Start         End      Blocks  Id  System
/dev/sda1    *         63   275803919  137901928+  7   HPFS/NTFS/exFat
/dev/sda2       275803290   317797829   20996955   83  Linux
/dev/sda3       317797954  1953520064  817861055+   5  Extended
/dev/sda5      1936716075  1953520064    8401995   82  Linux swap / Solaris

# blkid
/dev/sda1: UUID="4CD32DDF72FB084D" TYPE="ntfs"
/dev/sda2: UUID="dae0bc16-7133-4706-8a40-fdd84e281651" TYPE="ext4"
/dev/sda5: UUID="2daec68e-08b6-452f-8f75-2f59ebf61ba5" TYPE="swap"

这是我尝试自行安装时发生的情况

# mount /dev/sda3 /mnt
[ 2680.555298] EXT3-fs (sda3): error: unable to read superblock
[ 2680.564065] EXT4-fs (sda3): unable to read superblock
mout: you must specify the filesystem type

# mount -t ext4 /dev/sda3 /mnt
[ 2863.195328] EXT4-fs (sda3): unable to read superblock
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
... other stuff related to my sound card ...
[   21.538194] init: mountall main process (325) terminated with status 2
[ 2680.555298] EXT3-fs (sda3): error: unable to read superblock
[ 2680.564065] EXT4-fs (sda3): unable to read superblock
[ 2863.195328] EXT4-fs (sda3): unable to read superblock

然后，我在某处阅读以尝试

# mke2fs -n /dev/sda3
mke2fs 1.42 (29-Nov-2011)
mk2fs: inode_size (128) * inodes_count (0) too big for a
       fylesystem with 0 blocks, specify higher inode_ratio (-i)
       or lower inode count (-N).

# fsck.ext4 /dev/sda3
e2fsck 1.42 (29-Nov-2011)
fsck.ext4: Attempt to read block from filesystem resulted in short read
           while trying to open /dev/sda3
Could this be a zero-length partition?

基本上，似乎我的分区/ dev / sda3假定为零长度。

我该如何解决这个问题？