I tried to apply the recommendation of question:

Kernel Panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

After running that command:
sudo mount --bind /dev /mnt/dev

I get this error message:
mount: mount point /mnt/dev does not exist

fdisk -l returns

/dev/sda1

/dev/sda2

/dev/sda5

do I need to mount sda2 and sda5?

Edited after @psusi's comment:

/dev/sda1

is the boot file system

It seems that I need to mount sda2 or sda5. Here is what I tried:
(I tried this on a virtual machine so the sda(s) are now vda(s) )

ubuntu@ubuntu:~$ sudo fdisk -l



Disk /dev/vda: 19.3 GB, 19327352832 bytes

16 heads, 63 sectors/track, 37449 cylinders

Units = cylinders of 1008 * 512 = 516096 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk identifier: 0x0008eece



   Device Boot      Start         End      Blocks   Id  System

/dev/vda1   *           3         496      248832   83  Linux

Partition 1 does not end on cylinder boundary.

/dev/vda2             498       37448    18622465    5  Extended

Partition 2 does not end on cylinder boundary.

/dev/vda5             498       37448    18622464   8e  Linux LVM

ubuntu@ubuntu:~$ 

ubuntu@ubuntu:~$ 

ubuntu@ubuntu:~$ sudo mount -t ext4 /dev/vda5 /mnt

mount: wrong fs type, bad option, bad superblock on /dev/vda5,

       missing codepage or helper program, or other error

       In some cases useful info is found in syslog - try

       dmesg | tail  or so



ubuntu@ubuntu:~$ sudo mount -t ext2 /dev/vda5 /mnt

mount: wrong fs type, bad option, bad superblock on /dev/vda5,

       missing codepage or helper program, or other error

       In some cases useful info is found in syslog - try

       dmesg | tail  or so



ubuntu@ubuntu:~$

Any info that can help me rescue that server would be greatly appreciated!