After a system crash (which was caused by a hard restart), my Ubuntu linux is not booting, it is showing now:
error: uknown filesystem
grub rescue>
Solutions that I tried:
grub rescue>ls
(hd0) (hd0,msdos5) (hd0) (hd0,msdos1)
grub rescue>ls (hd0,msdos5)
error: uknown filesystem
grub rescue>ls (hd0,msdos1)
error: uknown filesystem
So, I can't list/find my Linux filesystem ,,,
I decided to try Boot Repair, installed on Ubuntu live USB, but there was no Recommended repair button and there was no Advanced options. There was only one button which is Create a BootInfo summary
I tried BootRepair on live versions of the latest Ubuntu and on Linux Secure Remix, they both are LIVE editions baked on USB - the same result.
Also OS-Uninstaller on Linux Secure Remix states that there is no found/installed OS.
I tried the same Linux Secure Remix on a different PC and at least there is Recommended repair. So I think the problem is in my HDD or MBR.
After some responses, I tried
root@ubuntu:/home/ubuntu# sudo fdisk -l
Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders, total 312581808 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: 0xebd671ce
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 302815231 151406592 83 Linux
/dev/sda2 302817278 312580095 4881409 5 Extended
/dev/sda5 302817280 312580095 4881408 82 Linux swap / Solaris
Disk /dev/sdb: 8021 MB, 8021606400 bytes
110 heads, 46 sectors/track, 3096 cylinders, total 15667200 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: 0x04030201
Device Boot Start End Blocks Id System
/dev/sdb1 * 10392 15667199 7828404 b W95 FAT32
root@ubuntu:/home/ubuntu# sudo mount /dev/sda1 /mnt
mount: you must specify the filesystem type
root@ubuntu:/home/ubuntu# blkid
/dev/loop0: TYPE="squashfs"
/dev/sda5: UUID="ce99d1c7-16fd-4b60-b0af-af6a14b8bdbe" TYPE="swap"
/dev/sdb1: LABEL="DANAIL" UUID="4ED6-708D" TYPE="vfat"
I tried different types: ext3, ext4, vfat and auto, but the result is same for all types:
root@ubuntu:/home/ubuntu# sudo mount -t ext4 /dev/sda1 /mnt
mount: wrong fs type, bad option, bad superblock on /dev/sda1,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
root@ubuntu:/home/ubuntu# dmesg | tail
[ 2424.052221] SQUASHFS error: Can't find a SQUASHFS superblock on sda1
[ 2620.531816] EXT4-fs (sda1): VFS: Can't find ext4 filesystem
[ 2626.204025] EXT3-fs (sda1): error: can't find ext3 filesystem on dev sda1.
[ 2626.208650] EXT4-fs (sda1): VFS: Can't find ext4 filesystem
[ 2626.208938] FAT-fs (sda1): bogus number of reserved sectors
[ 2626.208943] FAT-fs (sda1): Can't find a valid FAT filesystem
[ 2626.209377] SQUASHFS error: Can't find a SQUASHFS superblock on sda1
[ 2635.692959] EXT2-fs (sda1): error: can't find an ext2 filesystem on dev sda1.
[ 2644.614887] FAT-fs (sda1): bogus number of reserved sectors
[ 2644.614894] FAT-fs (sda1): Can't find a valid FAT filesystem
root@ubuntu:/home/ubuntu# mount
/cow on / type overlayfs (rw)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
/dev/sdb1 on /cdrom type vfat (ro,noatime,fmask=0022,dmask=0022,codepage=cp437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
/dev/loop0 on /rofs type squashfs (ro,noatime)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
none on /run/user type tmpfs (rw,noexec,nosuid,nodev,size=104857600,mode=0755)
gvfsd-fuse on /run/user/ubuntu/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,user=ubuntu)
Finally I found the solution was to run fsck
on the broken /dev/sda1
system. The problem is in the filesystem, not in grub. That's why grub can't see the filesystem. Thank you!