Some week ago I started having some problems with my pc, sometimes it just freezed not allowing me to do anything. I had to turn it off and on and sometimes do it a couple of time even at startup.

Now it does not start at all, grub is giving me error 18. I have found that a solution is to create a bootable partition in the first sector of the disk.
gparted does not recognize any partition, the window in which there would be my partitions is empty.
sudo fdisk -l does not output anything.
If I type sudo mount /dev/sda and then tab tab to autocomplete these are the devices coming out: sda sda1 sda2 sda5.
If I launch sudo mount -t ext3 /dev/sda1 disk I get the following error:

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

dmesg outputs

[ 1831.974847] EXT3-fs: unable to read superblock

Do you know how to solve this issue? I'm not completely sure this is a software problem, should I try with a new hard disk?